Employer's Quarterly Federal Tax Return

Instructions for Form CT-1 X
(Rev. April 2025)

Adjusted Employer's Annual Railroad Retirement Tax Return or Claim for Refund
Section references are to the Internal Revenue Code
unless otherwise noted.

Future Developments

For the latest information about developments related to
Form CT-1 X and its instructions, such as legislation
enacted after they were published, go to IRS.gov/CT1X.
Before you proceed with these instructions and

TIP completing Form CT-1 X, you'll need a copy of the

Instructions for Form CT-1 because these
instructions don't repeat all of the information included in
the Instructions for Form CT-1. For example, these
instructions don't discuss who is eligible to claim the credit
for qualified sick and family leave compensation or the
COBRA premium assistance credit. The current
Instructions for Form CT-1 are available at IRS.gov/CT1. If
you need a prior revision of the Instructions for Form CT-1,
select the link for "All Form CT-1 revisions" under "Other
items you may find useful."

What’s New
Period of limitations to make certain corrections expired; Form CT-1 X, lines 20a, 22, 23, 25a, 31, 32, 39,
and 40 are now reserved for future use. Lines 20a, 22,
23, 25a, 31, 32, 39, and 40 are now reserved for future
use because the period of limitations for correcting these
lines has generally expired for most employers. Generally,
you may correct overreported taxes on a previously filed
Form CT-1 if you file Form CT-1 X within 3 years of the
date Form CT-1 was filed or 2 years from the date you
paid the tax reported on Form CT-1, whichever is later.
You may correct underreported taxes on a previously filed
Form CT-1 if you file Form CT-1 X within 3 years of the
date the Form CT-1 was filed. We call each of these time
frames a period of limitations. For purposes of the period
of limitations, Form CT-1 for a calendar year is considered
filed on the last day of February of the succeeding year if
filed before that date. For an example of the period of
limitations, see Is There a Deadline for Filing Form CT-1 X,
later. Before using any line on Form CT-1 X, you must
consider if the period of limitations, as described above, is
still open for the year that you’re correcting.
Lines 22 and 23 were previously used to correct the
deferred amount of the Tier 1 Employer and Tier 1
Employee tax for 2020. The period of limitations for
making corrections to the deferred amount of the Tier 1
Employer and Tier 1 Employee tax generally expired for
most employers on February 29, 2024. These instructions
no longer discuss these deferrals. If you think that the
period of limitations is still open for correcting your 2020
Form CT-1, you can still file the March 2024 revision of
Form CT-1 X to use lines 22 and 23.
Lines 20a, 25a, 31, 32, 39, and 40 were used only
when correcting qualified compensation paid for the
Mar 17, 2025

employee retention credit and qualified health plan
expenses allocable to that compensation on a Form CT-1
filed for 2020 and 2021. The period of limitations for
making corrections to qualified compensation paid in 2020
for the employee retention credit and qualified health plan
expenses allocable to that compensation generally
expired for most employers on February 29, 2024. The
period of limitations for making corrections to qualified
compensation paid in 2021 for the employee retention
credit and qualified health plan expenses allocable to that
compensation generally expired for most employers on
February 28, 2025. Lines 39 and 40 were used only if your
business was a recovery startup business in the third or
fourth quarter of 2021. These instructions no longer
discuss these lines. If you think that the period of
limitations is still open for correcting your 2020 or 2021
Form CT-1, you can still file the March 2024 revision of
Form CT-1 X to use lines 20a, 25a, 31, 32, 39, and 40.

Reminders
If a line on Form CT-1 X doesn’t apply to you,
leave it blank. If you’re correcting a year before
CAUTION 2021, you must leave blank lines 20b, 20c, 20d,
25b, 25c, 33, 34, 35, 36, 37, and 38.

!

The COVID-19 related credit for qualified sick and
family leave compensation is limited to leave taken
after March 31, 2020, and before October 1, 2021,
and can no longer be claimed on Form CT-1.
Generally, the credit for qualified sick and family leave
compensation, as enacted under the Families First
Coronavirus Response Act (FFCRA) and amended and
extended by the COVID-related Tax Relief Act of 2020, for
leave taken after March 31, 2020, and before April 1,
2021, and the credit for qualified sick and family leave
compensation under sections 3131, 3132, and 3133 of
the Internal Revenue Code, as enacted under the
American Rescue Plan Act of 2021 (the ARP), for leave
taken after March 31, 2021, and before October 1, 2021,
have expired. However, employers that pay qualified sick
and family leave compensation in a later year for leave
taken after March 31, 2020, and before October 1, 2021,
are eligible to claim a credit for qualified sick and family
leave compensation paid in that year. Effective for tax
periods beginning after December 31, 2023, the lines
used to claim the credit for qualified sick and family leave
compensation were removed from Form CT-1 because it
would be extremely rare for an employer to pay
compensation after December 31, 2023, for qualified sick
and family leave taken after March 31, 2020, and before
October 1, 2021. Instead, if you're eligible to claim the
credit for qualified sick and family leave compensation
because you paid the compensation after December 31,
2023, for an earlier applicable leave period, file Form CT-1
X to claim the credit for qualified sick and family leave
compensation for the year that you paid the compensation

Instructions for Form CT-1 X (Rev. 4-2025) Catalog Number 20339E
Department of the Treasury Internal Revenue Service www.irs.gov

after you file Form CT-1. Filing a Form CT-1 X before filing
a Form CT-1 for the year may result in errors or delays in
processing your Form CT-1 X.
You will also continue to use Form CT-1 X to make
corrections to the credit for qualified sick and family leave
compensation for earlier years if the period of limitations is
still open. Corrections to amounts reported on Form CT-1,
lines 16, 23, 30, 31, 32, and 33, for the credit for qualified
sick and family leave compensation for leave taken after
March 31, 2020, and before April 1, 2021, are reported on
Form CT-1 X, lines 19, 24, 27, 28, 29, and 30,
respectively. Corrections to amounts reported on Form
CT-1, lines 17b, 24b, 36, 37, 38, 39, 40, and 41, for the
credit for qualified sick and family leave compensation for
leave taken after March 31, 2021, and before October 1,
2021, are reported on Form CT-1 X, lines 20b, 25b, 33,
34, 35, 36, 37, and 38, respectively.
Credit for COBRA premium assistance payments is
limited to periods of coverage beginning on or after
April 1, 2021, through periods of coverage beginning
on or before September 30, 2021. Section 9501 of the
ARP provides for COBRA premium assistance in the form
of a full reduction in the premium otherwise payable by
certain individuals and their families who elect COBRA
continuation coverage due to a loss of coverage as the
result of a reduction in hours or an involuntary termination
of employment (assistance eligible individuals). This
COBRA premium assistance was available for periods of
coverage beginning on or after April 1, 2021, through
periods of coverage beginning on or before September
30, 2021. A premium payee was entitled to the COBRA
premium assistance credit at the time an eligible individual
elects coverage. Therefore, other than in rare
circumstances, due to the COBRA notice and election
period requirements (generally, employers have 60 days
to provide notice and assistance eligible individuals have
60 days to elect coverage), January 2022 was generally
the end of the period in which an assistance eligible
individual would have elected coverage. Under some rare
circumstances, it may be possible for a premium payee to
become entitled to the COBRA premium assistance credit
after January 2022. In these rare instances, the credit was
still claimed on Form CT-1 filed for 2022 and an
adjustment, if needed, can be made on Form CT-1 X for
2022. Employers eligible to claim the COBRA premium
assistance credit after 2022 must file Form CT-1 X to
claim the credit.
For more information on COBRA premium assistance
payments and the credit, see Notice 2021-31, 2021-23
I.R.B. 1173, available at IRS.gov/irb/
2021-23_IRB#NOT-2021-31; and Notice 2021-46,
2021-33 I.R.B. 303, available at IRS.gov/irb/
2021-33_IRB#NOT-2021-46.
Corrections to amounts reported on Form CT-1, lines
17c, 17d, and 24c, for the COBRA premium assistance
credit are reported on Form CT-1 X, lines 20c, 20d, and
25c, respectively.
If you claimed the credit for qualified sick and
family leave compensation for leave taken after
CAUTION March 31, 2020, and before April 1, 2021, and you
make any corrections on Form CT-1 X to amounts used to
figure this credit, you'll need to refigure the amount of this

!

2

credit using Worksheet 1. You'll also use this worksheet to
figure this credit if you’re claiming it for the first time on
Form CT-1 X. If you claimed the credit for qualified sick
and family leave compensation for leave taken after March
31, 2021, and before October 1, 2021, and you make any
corrections on Form CT-1 X to amounts used to figure this
credit, you'll need to refigure the amount of this credit
using Worksheet 2. You'll also use this worksheet to figure
this credit if you’re claiming it for the first time on Form
CT-1 X. If you claimed the COBRA premium assistance
credit and you make any corrections on Form CT-1 X to
amounts used to figure this credit, you'll need to refigure
the amount of this credit using Worksheet 3. You'll also
use this worksheet to figure this credit if you’re claiming it
for the first time on Form CT-1 X.
Employee consents to support a claim for refund.
Rev. Proc. 2017-28, 2017-14 I.R.B. 1061, available at
IRS.gov/irb/2017-14_IRB#RP-2017-28, provides
guidance to employers on the requirements for employee
consents used by an employer to support a claim for
refund of overcollected Railroad Retirement Tax Act
(RRTA) taxes. The revenue procedure clarifies the basic
requirements for both a request for employee consent and
for the employee consent, and permits a consent to be
requested, furnished, and retained in an electronic format
as an alternative to paper format. The revenue procedure
also contains guidance concerning when an employer
may claim a refund of only the employer share of
overcollected RRTA taxes. The revenue procedure
requires that any request for consent include an Additional
Medicare Tax notice indicating that any claim on the
employee’s behalf won’t include a claim for overpaid Tier 1
Employee Additional Medicare Tax.
Correcting Tier 1 Employee Additional Medicare Tax
withholding and compensation subject to Tier 1 Employee Additional Medicare Tax withholding.
Compensation (including tips) and sick pay subject to Tier
1 Employee Additional Medicare Tax withholding are
reported on Form CT-1, lines 6 and 12. Certain errors
discovered on a previously filed Form CT-1 are corrected
on Form CT-1 X, lines 11 and 17. However, you can’t file
Form CT-1 X to correct Tier 1 Employee Additional
Medicare Tax actually withheld from an employee in a
prior year. See the instructions for lines 11 and 17, later,
for more information on the types of errors that can be
corrected and how the correction is reported on Form
CT-1 X. For more information about Tier 1 Employee
Additional Medicare Tax withholding, see the Instructions
for Form CT-1 or go to IRS.gov/ADMTfaqs.

General Instructions:
Understanding Form CT-1 X
What Is the Purpose of Form CT-1 X?
Use Form CT-1 X to correct errors on a previously filed
Form CT-1. Use Form CT-1 X to correct:
• Tier 1 Employee tax, Tier 1 Employee Medicare tax,
Tier 1 Employee Additional Medicare Tax, and Tier 2
Employee tax;

Instructions for Form CT-1 X (Rev. 4-2025)

• Tier 1 Employer tax, Tier 1 Employer Medicare tax, and
Tier 2 Employer tax;
• Amounts reported on Form CT-1 for the credit for
qualified sick and family leave compensation for leave
taken after March 31, 2020, and before April 1, 2021,
including adjustments to Form CT-1, lines 16, 23, 30, 31,
32, and 33;
• Amounts reported on Form CT-1 for the credit for
qualified sick and family leave compensation for leave
taken after March 31, 2021, and before October 1, 2021,
including adjustments to Form CT-1, lines 17b, 24b, 36,
37, 38, 39, 40, and 41; and
• Amounts reported on Form CT-1 for the COBRA
premium assistance credit, for periods of coverage
beginning on or after April 1, 2021, through periods of
coverage beginning on or before September 30, 2021,
including adjustments to Form CT-1, lines 17c, 17d, and
24c.
Use Form 843, Claim for Refund and Request for
Abatement, to request a refund or abatement of assessed
interest or penalties. Don’t request a refund or abatement
of assessed interest or penalties on Form CT-1 or Form
CT-1 X.
We use the terms “correct” and “corrections” on

TIP Form CT-1 X and in these instructions to include

interest-free adjustments under sections 6205 and
6413 and claims for refund and abatement under sections
6402, 6414, and 6404. See Rev. Rul. 2009-39 for
examples of how the interest-free adjustment and claim
for refund rules apply in 10 different situations. You can
find Rev. Rul. 2009-39, 2009-52 I.R.B. 951 at IRS.gov/irb/
2009-52_IRB#RR-2009-39.
When you discover an error on a previously filed Form
CT-1, you must:
• Correct that error using Form CT-1 X;
• File a separate Form CT-1 X for each Form CT-1 that
you’re correcting; and
• Generally, file Form CT-1 X separately. Don’t file Form
CT-1 X with Form CT-1. However, see the instructions for
line 42, later, for an exception.
If you didn’t file a Form CT-1 for 1 or more years, don’t
use Form CT-1 X. Instead, file Form CT-1 for each of
those years. Also, see When Should You File Form CT-1
X, later. However, if you didn’t file Forms CT-1 because
you improperly treated workers as independent
contractors or nonemployees and are now reclassifying
them as employees, see the instructions for line 42, later.
Unless otherwise specified in these instructions,
TIP an underreported employment tax credit should
be treated like an overreported tax amount. An
overreported employment tax credit should be treated like
an underreported tax amount. For more information,
including which process to select on lines 1 and 2, see
Correcting an employment tax credit, later.
Report the correction of underreported and
overreported tax amounts for the same tax period on a
single Form CT-1 X, unless you’re requesting a refund or
abatement. If you’re requesting a refund or abatement and
are correcting both underreported and overreported tax
amounts, file one Form CT-1 X correcting the
Instructions for Form CT-1 X (Rev. 4-2025)

underreported tax amounts only and a second Form CT-1
X correcting the overreported tax amounts.
You’ll use the adjustment process if you underreported
RRTA taxes and are making a payment, or if you
overreported RRTA taxes and will be applying the credit to
Form CT-1 for the period during which you file Form CT-1
X. However, see the Caution under Is There a Deadline for
Filing Form CT-1 X, later, if you’re correcting overreported
tax amounts during the last 90 days of a period of
limitations. You’ll use the claim process if you overreported
RRTA taxes and are requesting a refund or abatement of
the overreported tax amount. Follow the chart on page 6
of Form CT-1 X for help in choosing whether to use the
adjustment process or the claim process. Be sure to
provide a detailed explanation on line 43 for each
correction that you show on Form CT-1 X.
Continue to report current year adjustments on Form
CT-1, line 14.
You have additional requirements to complete when
filing Form CT-1 X, such as certifying that you filed (or will
file) all applicable Forms W-2, Wage and Tax Statement,
and Forms W-2c, Corrected Wage and Tax Statement,
with the Social Security Administration (SSA). For
corrections of overreported Tier 1 and Tier 2 taxes, you
must make any certifications that apply to your situation.
Be sure to give us a detailed explanation on line 43 for
each correction you show on Form CT-1 X.
Don’t use Form CT-1 X to correct Form 941,
941-SS, 943, 944, or 945. Instead, use the "X"
CAUTION form that corresponds to those forms (Form
941-X, 943-X, 944-X, or 945-X).

!

Where Can You Get Help?
For help filing Form CT-1 X or for questions about RRTA
taxes and tax corrections, you can:
• Go to IRS.gov/EmploymentTaxes and IRS.gov/
CorrectingEmploymentTaxes;
• See Pub. 15, Employer's Tax Guide; or
• Call the IRS Business and Specialty Tax Line toll free at
800-829-4933 or 800-829-4059 (TDD/TTY for persons
who are deaf, hard of hearing, or have a speech
disability), Monday–Friday from 7:00 a.m. to 7:00 p.m.
local time (Alaska and Hawaii follow Pacific time).
See also How Can You Get Forms, Instructions, and
Publications From the IRS, later.

When Should You File Form CT-1 X?
File Form CT-1 X when you discover an error on a
previously filed Form CT-1.
However, if your only errors on Form CT-1 relate to
RRTA tax liabilities reported in Part II of Form CT-1 or on
Form 945-A, Annual Record of Federal Tax Liability, don’t
file Form CT-1 X. To correct federal tax liabilities reported
in Part II of Form CT-1, file Form 945-A, but only enter the
monthly totals. The daily entries aren’t required. For more
information about correcting RRTA tax liabilities reported
on Form 945-A, see the Instructions for Form 945-A.
Due dates. The due date for filing Form CT-1 X depends
on when you discover an error and if you underreported or
3

overreported tax. If you underreported tax, see
Underreported tax, later. For overreported tax amounts,
you may choose to either make an interest-free
adjustment or file a claim for refund or abatement. If you’re
correcting overreported tax amounts, see Overreported
tax—Adjustment process or Overreported tax—Claim
process, later.
If any due date falls on a Saturday, Sunday, or legal
holiday, you may file Form CT-1 X on the next business
day. The term “legal holiday” means any legal holiday in
the District of Columbia. See Pub. 15 for the list of legal
holidays. If we receive Form CT-1 X after the due date, we
will treat Form CT-1 X as filed on time if the envelope
containing Form CT-1 X is properly addressed, contains
sufficient postage, and is postmarked by the U.S. Postal
Service (USPS) on or before the due date, or sent by an
IRS-designated private delivery service (PDS) on or
before the due date. If you don’t follow these guidelines,
we will consider Form CT-1 X filed when it is actually
received. For more information about PDSs, see Where
Should You File Form CT-1 X, later.
Underreported tax. If you’re correcting underreported
tax, you must file Form CT-1 X by the due date of the
return for the return period in which you discovered the
error and pay the amount you owe by the time you file.
Filing and paying on time generally will ensure that your
correction is interest free and not subject to failure-to-pay
(FTP) or failure-to-deposit (FTD) penalties. See What
About Penalties and Interest, later. For details on how to
make a payment, see the instructions for line 26, later.
If Form CT-1 X is filed late (after the due date of the
return for the return period in which you discovered the
error), you must attach an amended Form 945-A to Form
CT-1 X. Otherwise, the IRS may assess an “averaged”
FTD penalty. See “Averaged” FTD penalty in section 11 of
Pub. 15 for more information about “averaged” FTD
penalties. The total tax reported on Form 945-A, line M,
must match the corrected total tax (Form CT-1, line 15
(line 19 for tax years 2020–2023), combined with any
correction reported on Form CT-1 X, line 21) for the year,
less any previous abatements and interest-free tax
assessments.
Example—You owe tax. On March 14, 2025, you
discovered that you underreported $1,000 of RRTA
compensation on your 2024 Form CT-1. File Form CT-1 X
and pay the amount you owe by March 2, 2026 (February
28, 2026, is a Saturday), because you discovered the
error in 2025, and March 2, 2026, is the due date for that
year. If you file Form CT-1 X before March 2, 2026, pay the
amount you owe by the time you file.
Form CT-1 X can’t be used to correct
underreported amounts of Tier 1 Employee
CAUTION Additional Medicare Tax unless the amounts were
withheld from employee compensation.

!

Overreported tax—Adjustment process. If you
overreported tax and choose to apply the credit to Form
CT-1, file an adjusted return on Form CT-1 X as soon as
possible after you discover the error but more than 90
days before the period of limitations on the credit or refund
for Form CT-1 expires. See Is There a Deadline for Filing
Form CT-1 X, later.
4

Form CT-1 X can’t be used to correct overreported
amounts of Tier 1 Employee Additional Medicare
CAUTION Tax unless the amounts weren’t withheld from
employee compensation.

!

Example—You want your credit applied to Form
CT-1. You filed your 2024 Form CT-1 on February 24,
2025, and payments were timely made. On May 5, 2025,
you discover that you overreported tax on your 2024 Form
CT-1. You file Form CT-1 X on June 3, 2025, and check
the box on line 1 to indicate you want to use the
adjustment process. The IRS treats your credit as a tax
deposit made on January 1, 2025. When you file your
2025 Form CT-1, include the amount from Form CT-1 X,
line 26, on the “Total railroad retirement tax deposits” line
of your 2025 Form CT-1.
Overreported tax—Claim process. If you overreported
tax on Form CT-1, you may choose to file a claim for
refund or abatement on Form CT-1 X any time before the
period of limitations on credit or refund for Form CT-1
expires. If you also need to correct any underreported tax
amounts, you must file another Form CT-1 X reporting
only corrections to the underreported tax amounts. See Is
There a Deadline for Filing Form CT-1 X, later.

!

CAUTION

You may not file a refund claim to correct Tier 1
Employee Additional Medicare Tax actually
withheld from employees.

Is There a Deadline for Filing Form
CT-1 X?
Generally, you may correct overreported taxes on a
previously filed Form CT-1 if you file Form CT-1 X within 3
years of the date Form CT-1 was filed or 2 years from the
date you paid the tax reported on Form CT-1, whichever is
later. You may correct underreported taxes on a previously
filed Form CT-1 if you file Form CT-1 X within 3 years of
the date the Form CT-1 was filed. We call each of these
time frames a period of limitations. For purposes of the
period of limitations, Form CT-1 is considered filed on the
last day in February of the succeeding year if filed before
that date.
Example. You filed your 2022 Form CT-1 on January
30, 2023, and payments were timely made. The IRS treats
the return as if it were filed on February 28, 2023. On
January 15, 2026, you discover that you overreported
RRTA compensation on that form by $10,000. To correct
the error, you must file Form CT-1 X by March 2, 2026
(February 28, 2026, is a Saturday), which is the end of the
period of limitations, and use the claim process.
If you file Form CT-1 X to correct overreported tax
amounts in the last 90 days of a period of
CAUTION limitations, you must use the claim process. You
can’t use the adjustment process. If you are also
correcting underreported tax amounts, you must file
another Form CT-1 X to correct the underreported tax
amounts using the adjustment process and pay any tax
due.

!

Where Should You File Form CT-1 X?
Send your completed Form CT-1 X to:
Instructions for Form CT-1 X (Rev. 4-2025)

Department of the Treasury
Internal Revenue Service Center
Cincinnati, OH 45999-0007
PDSs can’t deliver to P.O. boxes. You must use the USPS
to mail an item to a P.O. box address. Go to IRS.gov/PDS
for the current list of PDSs. If you file Form CT-1 X using a
PDS, send it to the following address.
Ogden-Internal Revenue Submission Processing
Center
1973 Rulon White Blvd.
Ogden, UT 84201
Use this address even though Form CT-1 X mailed
through the USPS goes to Cincinnati.

How Should You Complete Form CT-1
X?
Use a Separate Form CT-1 X for Each Year You’re
Correcting

Use a separate Form CT-1 X for each Form CT-1 that
you’re correcting. For example, if you found errors on your
Forms CT-1 for 2023 and 2024, file one Form CT-1 X to
correct the 2023 Form CT-1. File a second Form CT-1 X to
correct the 2024 Form CT-1.

Employer Identification Number (EIN), RRB
Number, Name, and Address

Enter your EIN, RRB number, name, and address in the
spaces provided. Also enter your name and EIN on the
top of pages 2, 3, 4, and 5, and on any attachments. If
your address has changed since you filed your Form
CT-1, enter the corrected information and the IRS will
update your address of record. Be sure to write your
name, EIN, “Form CT-1 X,” and the calendar year you’re
correcting on the top of any attachments.

Return You’re Correcting

Enter the calendar year of the Form CT-1 you’re correcting
in the box at the top of page 1. Enter the same calendar
year on pages 2, 3, 4, and 5.

Enter the Date You Discovered Errors

You must enter the date you discovered errors. You
discover an error when you have enough information to be
able to correct it. If you’re reporting several errors that you
discovered at different times, enter the earliest date you
discovered an error here. Report any subsequent dates
and related errors on line 43.

Must You Make an Entry on Each Line?

You must provide all of the information requested at the
top of page 1 of Form CT-1 X. You must check one box
(but not both) in Part 1. In Part 2, you must check the box
on line 3 and any applicable boxes on lines 4 and 5. In
Part 3, if any line doesn’t apply, leave it blank. Complete
Parts 4 and 5 as instructed.

Instructions for Form CT-1 X (Rev. 4-2025)

How Should You Report Negative Amounts?

Form CT-1 X uses negative numbers to show reductions
in tax (credits) and positive numbers to show additional
tax (amounts you owe).

When reporting a negative amount in columns 3 and 4,
use a minus sign instead of parentheses. For example,
enter “-10.59” instead of “(10.59).” However, if you’re
completing the return on your computer and your software
only allows you to use parentheses to report negative
amounts, you may use them.

How Should You Make Entries on Form CT-1 X?

You can help the IRS process Form CT-1 X timely and
accurately if you follow these guidelines.
• Type or print your entries.
• Use Courier font (if possible) for all typed or
computer-generated entries.
• Omit dollar signs. You may use commas and decimal
points, if desired. Enter dollar amounts to the left of any
preprinted decimal point and cents to the right of it.
• Always show an amount for cents, even if it is zero.
Don’t round entries to whole dollars.
• Complete all five pages and sign Form CT-1 X on
page 5.
• Staple multiple sheets in the upper-left corner.

What About Penalties and Interest?

Generally, your correction of an underreported tax amount
won’t be subject to an FTP penalty, an FTD penalty, or
interest if you:
• File on time (by the due date of the year in which you
discover the error),
• Pay the amount shown on line 26 by the time you file
Form CT-1 X,
• Enter the date you discovered the error, and
• Explain in detail the grounds and facts relied on to
support the correction.
No correction will be eligible for interest-free treatment
if any of the following apply.
• The underreported amounts relate to an issue that was
raised in an examination of a prior period.
• You knowingly underreported your employment tax
liability.
• You received a notice and demand for payment.
• You received a notice of determination under section
7436.
If you receive a notice about a penalty after you file this
return, reply to the notice with an explanation and we will
determine if you meet reasonable-cause criteria. Don’t
attach an explanation when you file your return.

Overview of the Process
To correct a previously filed Form CT-1, use Form CT-1 X
to file either an adjusted railroad retirement tax return or a
claim for refund or abatement. The adjustment process
and the claim process are outlined below.
If you underreported the tax. If you underreported
the tax on a previously filed Form CT-1, check the box on
line 1 and pay any additional amount you owe by the
time you file Form CT-1 X. For details on how to make a
payment, see the instructions for line 26, later.
5

Example—You underreported RRTA taxes. On June
20, 2025, you discovered an error that results in additional
tax on your 2024 Form CT-1. File Form CT-1 X by March
2, 2026 (February 28, 2026, is a Saturday), and pay the
amount you owe by the time you file. See When Should
You File Form CT-1 X, earlier. Don’t attach Form CT-1 X to
your 2025 Form CT-1.
If you overreported the tax. If you overreported the
tax on a previously filed Form CT-1, choose one of the
following options.
• Use the adjustment process. Check the box on line 1 to
apply any credit (negative amount) from line 26 to Form
CT-1 for the year during which you file Form CT-1 X.
• Use the claim process. Check the box on line 2 to file a
claim on Form CT-1 X requesting a refund or abatement of
the amount shown on line 26.
To ensure that the IRS has enough time to

TIP process a credit for an overreporting tax

adjustment in the year during which you file Form
CT-1 X, you’re encouraged to file Form CT-1 X correcting
the overreported tax amount in the first 11 months of a
year. For example, if you discover an overreported tax
amount in December, you may want to file Form CT-1 X in
the first 11 months of the next year. However, there must
be 90 days remaining on the period of limitations when
you file Form CT-1 X. See the Caution under Is There a
Deadline for Filing Form CT-1 X, earlier. This should
ensure that the IRS will have enough time to process the
Form CT-1 X so that the credit will be posted before you
file Form CT-1, thus avoiding an erroneous balance due
notice from the IRS. See the example next.
Example—You want your overreported tax applied
as a credit on Form CT-1. On December 19, 2025, you
discover you overreported your tax on your 2024 Form
CT-1 and want to choose the adjustment process. To
allow the IRS enough time to process the credit, you file
Form CT-1 X on March 10, 2026, and take the credit on
your 2026 Form CT-1.

Specific Instructions
Part 1: Select ONLY One Process
Because Form CT-1 X may be used to file either an
adjusted railroad retirement tax return or a claim for refund
or abatement, you must check one box on either line 1 or
line 2. Don’t check both boxes.
Correcting an employment tax credit. For boxes 1 and
2, if you underreported an employment tax credit, treat it
like you overreported a tax amount. If you overreported an
employment tax credit, treat it like you underreported a tax
amount. If you're filing Form CT-1 X to adjust only an
employment tax credit and you're not correcting any
overreported taxes on Form CT-1 X, lines 6–17, skip lines
4 and 5.

1. Adjusted Railroad Retirement Tax Return

Check the box on line 1 if you’re correcting underreported
tax amounts or overreported tax amounts and you would
like to use the adjustment process to correct the errors.

If you’re correcting both underreported tax amounts
and overreported tax amounts on this form, you must
check this box. If you check this box, any negative amount
shown on line 26 will be applied as a credit (tax deposit) to
your Form CT-1 for the year in which you’re filing this form.
See Example—You want your overreported tax applied as
a credit on Form CT-1, earlier.
Form CT-1 X can’t be used to correct overreported
amounts of Tier 1 Employee Additional Medicare
CAUTION Tax unless the amounts weren’t withheld from
employee compensation.

!

If you owe tax. Pay the amount shown on line 26 by the
time you file Form CT-1 X. Generally, you won’t be
charged interest if you file on time, pay on time, enter the
date you discovered the error, and explain the correction
on line 43.
If you have a credit. You overreported RRTA taxes (you
have a negative amount on line 26) and want the IRS to
apply the credit to Form CT-1 for the period during which
you filed Form CT-1 X. The IRS will apply your credit on
the first day of the Form CT-1 year during which you filed
Form CT-1 X. However, the credit you show on Form CT-1
X, line 26, may not be fully available on your Form CT-1 if
the IRS corrects it during processing or you owe other
taxes, penalties, or interest. The IRS will notify you if your
claimed credit changes or if the amount available as a
credit on Form CT-1 was reduced because of unpaid
taxes, penalties, or interest.
Don’t check the box on line 1 if you’re correcting
overreported tax amounts and the period of
CAUTION limitations on credit or refund for Form CT-1 will
expire within 90 days of the date you file Form CT-1 X.
Instead, check the box on line 2. See Is There a Deadline
for Filing Form CT-1 X, earlier.

!

2. Claim

Check the box on line 2 to use the claim process if you’re
correcting overreported tax amounts only and you’re
claiming a refund or abatement for the negative amount
(credit) shown on line 26. Don’t check this box if you’re
correcting any underreported tax amounts on this form.
You must check the box on line 2 if you have a credit (a
negative amount on line 26) and the period of limitations
on credit or refund for Form CT-1 will expire within 90 days
of the date you file Form CT-1 X. See Is There a Deadline
for Filing Form CT-1 X, earlier.
The IRS usually processes claims shortly after they are
filed. The IRS will notify you if your claim is denied,
accepted as filed, or selected to be examined. See Pub.
556, Examination of Returns, Appeal Rights, and Claims
for Refund, for more information.
Unless the IRS corrects Form CT-1 X during
processing or you owe other taxes, penalties, or interest,
the IRS will refund the amount shown on line 26, plus any
interest that applies.

!

CAUTION

6

You may not file a refund claim to correct Tier 1
Employee Additional Medicare Tax actually
withheld from employees.
Instructions for Form CT-1 X (Rev. 4-2025)

Part 2: Complete the Certifications
You must complete all certifications that apply by checking
the appropriate boxes. If all of your corrections relate to
underreported tax amounts, complete line 3 only; skip
lines 4 and 5 and go to Part 3.
If your corrections relate to overreported tax amounts,
other than corrections related to underreported
employment tax credits, you have a duty to ensure that
your employees' rights to recover overpaid Employee
RRTA taxes that you withheld are protected. The
certifications on lines 4 and 5 address the requirement to:

• Repay or reimburse your employees for the
overcollection of Employee RRTA taxes, or
• Obtain consents from your employees to file a claim on
their behalf. See Rev. Proc. 2017-28 for guidance on the
requirements for both a request for employee consent and
for the employee consent.
For purposes of these certifications, Employee RRTA
taxes consist of Tier 1 Employee tax, Tier 1 Employee
Medicare tax, and Tier 2 Employee tax. Employer RRTA
taxes consist of Tier 1 Employer tax, Tier 1 Employer
Medicare tax, and Tier 2 Employer tax.
3. Filing Forms W-2 or Forms W-2c

Check the box on line 3 to certify that you filed or will file
Forms W-2 or Forms W-2c with the SSA, as required,
showing your employees' correct wage and tax amounts.
See the General Instructions for Forms W-2 and W-3 for
detailed information about filing requirements.
You must check the box on line 3 to certify that you filed
Forms W-2 or Forms W-2c even if your corrections on
Form CT-1 X don’t change amounts shown on those
forms. For example, if your only correction to Form CT-1
involves misstated tax adjustments, which don’t change
the amounts reported on your employees’ Forms W-2 (see
the instructions for line 18, later), check the box on line 3
to certify that you already filed all required Forms W-2 and
W-2c with the SSA. In this situation, you’re certifying that
you don’t need to file Form W-2c because you already
filed a correct Form W-2.

4. Certifying Overreporting Adjustments

If you overreported RRTA tax and/or Tier 1 Employee
Additional Medicare Tax and checked the box on line 1,
check the appropriate box on line 4. You may need to
check more than one box. If you obtained written
statements from some employees but you couldn’t locate
employees or secure the statements of the remaining
employees, check all applicable boxes. Provide a
summary on line 43 of the amount of the corrections for
both the employees who provided written statements and
for those who didn’t.
You may not use Form CT-1 X to correct
overreported amounts of Tier 1 Employee
CAUTION Additional Medicare Tax unless the amounts
weren’t withheld from employee compensation.

!

4a. Check the box on line 4a if your overreported amount
includes each affected employee share of overcollected
Employee RRTA taxes. You’re certifying that you repaid or
reimbursed the prior year Employee RRTA taxes and you
Instructions for Form CT-1 X (Rev. 4-2025)

received written statements from the employees stating
that they didn’t and won’t receive a refund or credit for the
prior year taxes. Don’t send these statements to the IRS.
Keep them for your records. Generally, all employment tax
records must be kept for at least 4 years. Records related
to qualified sick leave compensation and qualified family
leave compensation for leave taken after March 31, 2021,
and before October 1, 2021, should be kept for at least 6
years. Copies must be submitted to the IRS if requested.
4b. Check the box on line 4b to certify that your
overreported amount is only for Employer RRTA taxes on
those employees whom you were unable to find or those
who didn’t give you a statement described on line 4a.
4c. Check the box on line 4c to certify that your
overreported amount is only for RRTA taxes and/or Tier 1
Employee Additional Medicare Tax that you didn’t withhold
from your employees.

5. Certifying Claims

If you’re filing a claim for refund or abatement of
overreported RRTA tax and/or Tier 1 Employee Additional
Medicare Tax and checked the box on line 2, check the
appropriate box on line 5. You may need to check more
than one box. If you obtained written statements or
consents from some employees but you couldn’t locate
employees or secure the statements of the remaining
employees, check all applicable boxes. Provide a
summary on line 43 of the amount of the corrections for
the employees who provided statements or consents and
those who didn’t.
You may not file a refund claim to correct Tier 1
Employee Additional Medicare Tax actually
CAUTION withheld from employees. If you request their
consent to file a claim for employee RRTA taxes you must
tell your employees that you can’t claim a refund of any
Tier 1 Employee Additional Medicare Tax on their behalf.
See Rev. Proc. 2017-28 for sample language to use in
your request.

!

5a. Check the box on line 5a if your overreported tax
includes overcollected Employee RRTA taxes for each
affected employee. You’re certifying that you repaid or
reimbursed the employees their shares of the prior year
Employee RRTA taxes and you received written
statements from those employees stating that they didn’t
and won’t receive a refund or credit for the prior year
taxes. Don’t send these statements to the IRS. Keep them
for your records. Generally, all employment tax records
must be kept for at least 4 years. Records related to
qualified sick leave compensation and qualified family
leave compensation for leave taken after March 31, 2021,
and before October 1, 2021, should be kept for at least 6
years. Copies must be submitted to the IRS if requested.
5b. Check the box on line 5b if your overreported tax
includes overcollected prior year Employee RRTA taxes
for each affected employee and you haven’t yet repaid or
reimbursed the Employee RRTA taxes. You’re certifying
that you received consent from each affected employee to
file a claim on the employee share of those taxes and you
received written statements from those employees stating
that they didn’t and won’t receive a refund or credit for the
prior year taxes.
7

An employee consent must:

• Contain the name, address, and social security number

(or truncated taxpayer identification number, when
appropriate) of the employee;
• Contain the name, address, and EIN of the employer;
• Contain the tax period(s), the type of tax, and the
amount of tax for which the consent is provided;
• Affirmatively state that the employee authorizes the
employer to claim a refund for the overpayment of the
employee share of tax;
• Include the employee's written statement certifying that
the employee hasn't made any previous claims (or the
claims were rejected) and won't make any future claims for
refund or credit of the amount of the overcollection;
• Identify the basis of the claim; and
• Be dated and contain the employee's signature under
penalties of perjury. The penalties of perjury statement
should be located immediately above the required
signature.
Don’t send these statements and consents to the IRS.
Keep them for your records. Generally, all employment tax
records must be kept for at least 4 years. Records related
to qualified sick leave compensation and qualified family
leave compensation for leave taken after March 31, 2021,
and before October 1, 2021, should be kept for at least 6
years. Copies must be submitted to the IRS if requested.
In certain situations, you may not have repaid or
reimbursed your employees or obtained their consents
prior to filing a claim, such as in cases where the period of
limitations on credit or refund is about to expire. In those
situations, file Form CT-1 X but don’t check a box on
line 5. Tell us on line 43 that you haven’t repaid or
reimbursed employees or obtained consents at the time
you file the claim. However, you must repay or reimburse
your employees and certify that you have done so before
the IRS can allow the claim.
5c. Check the box on line 5c to certify that your
overreported tax is only for the Employer RRTA taxes. This
applies when affected employees didn’t give you consent
to file a claim for refund for the Employee RRTA taxes,
they couldn’t be found, or they didn’t give you a statement
described on line 5b.
5d. Check the box on line 5d to certify that your
overreported amount is only for RRTA taxes and/or Tier 1
Employee Additional Medicare Tax that you didn’t withhold
from your employees.

Part 3: Enter the Corrections for the
Calendar Year You’re Correcting
What Amounts Should You Report in Part 3?

On lines 6–17, columns 1 and 2, show amounts for all of
your employees, not just for those employees whose
amounts you’re correcting.
If a correction that you report in column 4 includes both
underreported and overreported amounts (see the
instructions for line 41, later), provide details for each error
on line 43.

instructions for each line carefully before entering amounts
in the columns.
If any line doesn’t apply to you, leave it blank.
If you previously adjusted or amended Form CT-1
using Form CT-1 X, or because of an IRS
CAUTION examination change, show amounts in column 2
that include those previously reported corrections.

!

6. Tier 1 Employer Tax—Compensation
For purposes of these instructions, all references

TIP to “sick pay” mean ordinary sick pay, not “qualified
sick leave compensation.”

If you’re correcting the compensation (other than tips
and sick pay) for the Tier 1 Employer tax you reported on
Form CT-1, line 1, enter the total corrected amount for all
employees in column 1. In column 2, enter the amount you
originally reported or as previously corrected. In column 3,
enter the difference between columns 1 and 2. If you (or
the IRS) previously corrected the amount reported on
Form CT-1, line 1, enter in column 2 the amount after any
previous corrections.
line 6 (column 1)
- line 6 (column 2)
line 6 (column 3)

If the amount in column 2 is larger than
the amount in column 1, use a minus
sign in column 3.

Multiply the amount in column 3 by 0.062 (6.2% tax
rate) and enter the result in column 4.
line 6 (column 3)
x
0.062
line 6 (column 4)

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Example—Tier 1 Employer compensation
decreased. You reported $9,000 as Tier 1 Employer
compensation in computing the tax on line 1 of your 2024
Form CT-1. In December 2025, you discovered that you
included $2,000 in compensation for one of your
employees twice. To correct the error, figure the difference
on Form CT-1 X as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 1)

7,000.00
- 9,000.00

Column 3 (difference)

-2,000.00

Use the difference in column 3 to determine your tax
correction.
Column 3 (difference)
Tax rate (6.2%)
Column 4 (tax correction)

-2,000.00
x 0.062
-124.00

Because special circumstances apply for lines 18, 19,
20b–20d, 24, 25b, 25c, 27–30, and 33–38, read the
8

Instructions for Form CT-1 X (Rev. 4-2025)

Be sure to explain the reasons for this correction on
line 43.

line 8 (column 3)

7. Tier 1 Employer Medicare
Tax—Compensation

If you’re correcting the compensation (other than tips and
sick pay) for the Tier 1 Employer Medicare tax you
reported on Form CT-1, line 2, enter the total corrected
amount in column 1. In column 2, enter the amount you
originally reported or as previously corrected. In column 3,
enter the difference between columns 1 and 2.
line 7 (column 1)
- line 7 (column 2)
line 7 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Multiply the amount in column 3 by 0.0145 (1.45% tax
rate) and enter the result in column 4.
line 7 (column 3)
x 0.0145
line 7 (column 4)

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Example—Tier 1 Employer Medicare
compensation decreased. Following Example—Tier 1
Employer compensation decreased in the instructions for
line 6, the compensation that you counted twice was also
Tier 1 Employer Medicare compensation. To correct the
error, figure the difference on Form CT-1 X as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 2)

7,000.00
- 9,000.00

Column 3 (difference)

-2,000.00

Use the difference in column 3 to determine your tax
correction.
Column 3 (difference)
Tax rate (1.45%)
Column 4 (tax correction)

line 8 (column 1)
- line 8 (column 2)

-2,000.00
x 0.0145
-29.00

Be sure to explain the reasons for this correction on
line 43.

Multiply the amount in column 3 by the rate stated on
line 3 of the Form CT-1 for the year that you’re
correcting and enter the result in column 4. If the amount
in column 3 used a minus sign, also use a minus sign in
column 4.
Example—Tier 2 Employer compensation
decreased. Following Example—Tier 1 Employer
compensation decreased in the instructions for line 6, the
compensation that you counted twice was also Tier 2
Employer compensation. Because you’re correcting your
2024 Form CT-1 in this example, use the rate from line 3
(13.1%) shown on that return. To correct the error, figure
the difference on Form CT-1 X as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 3)

7,000.00
- 9,000.00

Column 3 (difference)

-2,000.00

Use the difference in column 3 to determine your tax
correction.
Column 3 (difference)
Tax rate (13.1%)

-262.00

Be sure to explain the reasons for this correction on
line 43.

9. Tier 1 Employee Tax—Compensation

If you’re correcting the compensation, including tips
reported, but excluding sick pay, for the Tier 1 Employee
tax you reported on Form CT-1, line 4, enter the total
corrected amount in column 1. In column 2, enter the
amount you originally reported or as previously corrected.
In column 3, enter the difference between columns 1 and
2.
line 9 (column 1)
- line 9 (column 2)
line 9 (column 3)

If the amount in column 2 is larger than
the amount in column 1, use a minus
sign in column 3.

Multiply the amount in column 3 by 0.062 (6.2% tax
rate) and report the result in column 4.
line 9 (column 3)
x 0.062
line 9 (column 4)

Instructions for Form CT-1 X (Rev. 4-2025)

-2,000.00
x 0.131

Column 4 (tax correction)

8. Tier 2 Employer Tax—Compensation

If you’re correcting the compensation (other than tips) for
the Tier 2 Employer tax you reported on Form CT-1, line 3,
enter the total corrected amount in column 1. In column 2,
enter the amount you originally reported or as previously
corrected. In column 3, enter the difference between
columns 1 and 2.

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

9

Be sure to explain the reasons for this correction on
line 43.

10. Tier 1 Employee Medicare
Tax—Compensation

If you’re correcting the compensation, including tips
reported, but excluding sick pay, for the Tier 1 Employee
Medicare tax you reported on Form CT-1, line 5, enter the
total corrected amount in column 1. In column 2, enter the
amount you originally reported or as previously corrected.
In column 3, enter the difference between columns 1 and
2.
line 10 (column 1)
- line 10 (column 2)
line 10 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

line 10 (column 3)
x 0.0145
If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Be sure to explain the reasons for this correction on
line 43.

11. Tier 1 Employee Additional Medicare
Tax—Compensation (Other Than Sick Pay)

You may use Form CT-1 X to correct errors to Tier 1
Employee Additional Medicare Tax withholding for prior
years if the amount reported on Form CT-1, line 6, isn’t the
amount you actually withheld. This type of error is an
administrative error. The administrative error adjustment
corrects the amount reported on Form CT-1 to agree with
the amount actually withheld from employees.
If a prior year error was a nonadministrative error, you
may correct only the compensation subject to Tier 1
Employee Additional Medicare Tax withholding that was
originally reported on Form CT-1, line 6, or previously
corrected on Form CT-1 X. You can’t correct the tax
reported on Form CT-1, line 6.
Prior year administrative errors. If you’re correcting the
compensation subject to Tier 1 Employee Additional
Medicare Tax withholding that you reported on Form CT-1,
line 6, enter the total corrected amount in column 1. In
column 2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2.

10

line 11 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Multiply the amount in column 3 by 0.009 (0.9% tax
rate) and enter the result in column 4.
line 11 (column 3)
x 0.009
line 11 (column 4)

Multiply the amount in column 3 by 0.0145 (1.45% tax
rate) and enter the result in column 4.

line 10 (column 4)

line 11 (column 1)
- line 11 (column 2)

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Example—Prior year administrative error
(incorrectly reported amount of Tier 1 Employee
Additional Medicare Tax actually withheld). Nathan
Smith's compensation exceeded the $200,000
withholding threshold for Tier 1 Employee Additional
Medicare Tax in November 2024. The total compensation
paid to Nathan for 2024 was $230,000. You withheld $270
($30,000 x 0.009) from Nathan's compensation. However,
on your 2024 Form CT-1 you mistakenly reported $3,000
on line 6 (Compensation column), and Tier 1 Employee
Additional Medicare Tax withheld of $27 on line 6 (Tax
column). You discovered the error on March 17, 2025.
This is an example of an administrative error that may be
corrected in a later calendar year because the amount
actually withheld differs from the amount reported on your
2024 Form CT-1. Use Form CT-1 X, line 11, to correct the
error as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 6
(Compensation column))
Column 3 (difference)

30,000.00
- 3,000.00
27,000.00

Use the difference in column 3 to determine your tax
correction.
Column 3 (difference)
Tax rate (0.9%)
Column 4 (tax correction)

27,000.00
x 0.009
243.00

Be sure to explain the reasons for this correction on
line 43.
Prior year nonadministrative errors. You may correct
only the compensation subject to Tier 1 Employee
Additional Medicare Tax withholding that you reported on
Form CT-1, line 6 (Compensation column). Enter the total
corrected amount in column 1. In column 2, enter the
amount you originally reported or as previously corrected.
In column 3, enter the difference between columns 1 and
2.

Instructions for Form CT-1 X (Rev. 4-2025)

line 11 (column 1)
- line 11 (column 2)
line 11 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Don’t multiply the amount in column 3 by 0.009 (0.9%
tax rate). Leave column 4 blank and explain the reasons
for this correction on line 43.
Example—Prior year nonadministrative error
(failure to withhold Tier 1 Employee Additional
Medicare Tax when required). Leah Green's
compensation exceeded the $200,000 withholding
threshold for Tier 1 Employee Additional Medicare Tax in
December 2024. The total compensation paid to Leah for
2024 was $220,000. You were required to withhold $180
($20,000 x 0.009) but you withheld nothing and didn’t
report an amount on line 6 of your 2024 Form CT-1. You
discovered the error on March 17, 2025. File Form CT-1 X
to correct the compensation subject to Tier 1 Employee
Additional Medicare Tax withholding for your 2024 Form
CT-1, but you may not correct the Tier 1 Employee
Additional Medicare Tax withheld (column 4) because the
error involves a previous year and the amount previously
reported for the employee represents the actual amount
withheld from the employee during 2024.
Combination of prior year administrative and nonadministrative errors. If you’re reporting both
administrative errors and nonadministrative errors for the
same prior year, enter the total corrected amount in
column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. However, multiply
only the amount of compensation reported in column 3
that is related to administrative errors by 0.009 (0.9% tax
rate). Don’t multiply any compensation reported in column
3 that was related to nonadministrative errors by 0.009
(0.9% tax rate). Use line 43 to explain in detail your
corrections. The explanation must include the reasons for
the corrections and a breakdown of the amount reported
in column 3 into the amounts related to administrative
errors and nonadministrative errors.
Example—Combination of prior year
administrative and nonadministrative errors. Nathan
Smith's compensation exceeded the $200,000
withholding threshold for Tier 1 Employee Additional
Medicare Tax in November 2024. The total compensation
paid to Nathan for 2024 was $230,000. You withheld $270
($30,000 x 0.009) from Nathan's compensation. However,
on your 2024 Form CT-1, you mistakenly reported $3,000
on line 6 (Compensation column), and Tier 1 Employee
Additional Medicare Tax withheld of $27 on line 6 (Tax
column). The difference in compensation subject to Tier 1
Employee Additional Medicare Tax related to this
administrative error is $27,000 ($30,000 - $3,000).
Leah Green's compensation exceeded the $200,000
withholding threshold for Tier 1 Employee Additional
Medicare Tax in December 2024. The total compensation
paid to Leah for 2024 was $220,000. You were required to
withhold $180 ($20,000 x 0.009) but you withheld nothing
Instructions for Form CT-1 X (Rev. 4-2025)

and didn’t report Leah's $20,000 in compensation subject
to Tier 1 Employee Additional Medicare Tax withholding
on line 6 of your 2024 Form CT-1.
You discovered both errors on March 17, 2025. Use
Form CT-1 X, line 11, to correct the errors as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 6
(Compensation column))
Column 3 (difference)

50,000.00
- 3,000.00
47,000.00

Determine the portion of compensation reported in
column 3 that is related to the administrative error
($47,000 - $20,000 (nonadministrative error) = $27,000
(administrative error)). Multiply this portion of column 3 by
0.009 (0.9% tax rate) to determine your tax correction.
Difference related to administrative error
Tax rate (0.9%)
Column 4 (tax correction)

27,000.00
x 0.009
243.00

Be sure to explain the reasons for these corrections on
line 43. You must also report that $20,000 of the amount
shown in column 3 was related to the correction of a prior
year nonadministrative error and $27,000 of the amount
shown in column 3 was related to the correction of an
administrative error.

12. Tier 2 Employee Tax—Compensation

If you’re correcting the compensation, including tips
reported, for the Tier 2 Employee tax you reported on
Form CT-1, line 7, enter the total corrected amount in
column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2.
line 12 (column 1)
- line 12 (column 2)
line 12 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Multiply the amount in column 3 by the rate stated on
line 7 of the Form CT-1 for the year that you’re
correcting and enter the result in column 4. If the amount
in column 3 used a minus sign, also use a minus sign in
column 4.
Example—Tier 2 Employee compensation
decreased. Following Example—Tier 1 Employer
compensation decreased in the instructions for line 6, the
compensation that you counted twice was also Tier 2
Employee compensation. Because you’re correcting your
2024 Form CT-1 in this example, use the rate for line 7
(4.9%) shown on that return. To correct the error, figure
the difference on Form CT-1 X as shown.

11

Column 1 (corrected amount)
Column 2 (Form CT-1, line 7)

7,000.00
- 9,000.00

Column 3 (difference)
Tax rate (6.2%)

Column 3 (difference)

-2,000.00

Column 4 (tax correction)

Use the difference in column 3 to determine your tax
correction.
Column 3 (difference)
Tax rate (4.9%)

-2,000.00
x 0.049

Column 4 (tax correction)

-98.00

Be sure to explain the reasons for this correction on
line 43.
For purposes of these instructions, all references

TIP to “sick pay” mean ordinary sick pay, not “qualified
sick leave compensation.”

14. Tier 1 Employer Medicare Tax—Sick Pay

If you’re correcting the sick pay for the Tier 1 Employer
Medicare tax you reported on Form CT-1, line 9, enter the
total corrected amount in column 1. In column 2, enter the
amount you originally reported or as previously corrected.
In column 3, enter the difference between columns 1 and
2.
line 14 (column 1)
- line 14 (column 2)
If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

13. Tier 1 Employer Tax—Sick Pay

line 13 (column 1)
- line 13 (column 2)
If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Multiply the amount in column 3 by 0.062 (6.2% tax
rate) and enter the result in column 4.
line 13 (column 3)
x 0.062
line 13 (column 4)

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Example—Tier 1 Employer sick pay increased. You
reported $8,000 as Tier 1 Employer sick pay in computing
the tax on line 8 of your 2024 Form CT-1. In December
2025, you discover that you overlooked $1,000 in sick pay
for one of your employees. To correct the error, figure the
difference on Form CT-1 X as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 8)
Column 3 (difference)

Multiply the amount in column 3 by 0.0145 (1.45% tax
rate) and enter the result in column 4.
line 14 (column 3)
x 0.0145
line 14 (column 4)

line 13 (column 3)

9,000.00
- 8,000.00
1,000.00

Use the difference in column 3 to determine your tax
correction.

62.00

Be sure to explain the reasons for this correction on
line 43.

line 14 (column 3)

If you’re correcting the sick pay for the Tier 1 Employer tax
you reported on Form CT-1, line 8, enter the total
corrected amount in column 1. In column 2, enter the
amount you originally reported or as previously corrected.
In column 3, enter the difference between columns 1 and
2.

1,000.00
x 0.062

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Be sure to explain the reasons for this correction on
line 43.

15. Tier 1 Employee Tax—Sick Pay

If you’re correcting the sick pay for the Tier 1 Employee tax
you reported on Form CT-1, line 10, enter the total
corrected amount in column 1. In column 2, enter the
amount you originally reported or as previously corrected.
In column 3, enter the difference between columns 1 and
2.
line 15 (column 1)
- line 15 (column 2)
line 15 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Multiply the amount in column 3 by 0.062 (6.2% tax
rate) and enter the result in column 4.
line 15 (column 3)
x 0.062
line 15 (column 4)

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Be sure to explain the reasons for this correction on
line 43.
12

Instructions for Form CT-1 X (Rev. 4-2025)

16. Tier 1 Employee Medicare Tax—Sick Pay

If you’re correcting the sick pay for the Tier 1 Employee
Medicare tax you reported on Form CT-1, line 11, enter
the total corrected amount in column 1. In column 2, enter
the amount you originally reported or as previously
corrected. In column 3, enter the difference between
columns 1 and 2.
line 16 (column 1)
- line 16 (column 2)
line 16 (column 3)

If the amount in column 2 is larger
than the amount in column 1, use a
minus sign in column 3.

Multiply the amount in column 3 by 0.0145 (1.45% tax
rate) and enter the result in column 4.
line 16 (column 3)
x 0.0145
line 16 (column 4)

If the amount in column 3 used a minus sign,
also use a minus sign in column 4.

Be sure to explain the reasons for this correction on
line 43.

17. Tier 1 Employee Additional Medicare
Tax—Sick Pay

You may need to report negative numbers in any

TIP column. Make sure that the difference you enter in

column 3 accurately represents the change to
adjustments originally reported or previously corrected on
Form CT-1, line 14.
Copy the amount in column 3 to column 4. Include any
minus sign shown in column 3.
On line 43, describe what you misreported on Form
CT-1. Tell us which current year adjustments have
changed, that is, fractions of cents; uncollected Tier 1
Employee tax, Tier 1 Employee Medicare tax, or Tier 2
Employee tax on tips; or credits for overpayments of
penalties or interest paid on tax for earlier years.
Only use line 18 to correct adjustments for
fractions of cents; uncollected Tier 1 Employee
CAUTION tax, Tier 1 Employee Medicare tax, Tier 1
Employee Additional Medicare Tax, and Tier 2 Employee
tax on tips; or credits for overpayments of penalty or
interest previously reported. File a separate Form CT-1 X
for each year being corrected.

!

Form CT-1 X and these instructions use the terms

TIP “nonrefundable” and “refundable” when

discussing credits. The term “nonrefundable”
means the portion of the credit which is limited by law to
certain taxes. The term “refundable” means the portion of
the credit which is in excess of those taxes.

You may use Form CT-1 X to correct errors to Tier 1
Employee Additional Medicare Tax withholding for prior
years if the amount reported on Form CT-1, line 12, isn’t
the amount you actually withheld. This type of error is an
administrative error.
If a prior year error was a nonadministrative error, you
may correct only the sick pay subject to Tier 1 Employee
Additional Medicare Tax withholding that was originally
reported on Form CT-1, line 12, or previously corrected on
Form CT-1 X. You can’t correct the tax reported on Form
CT-1, line 12.
For more information on the types of errors that can be
corrected on line 17, see the detailed examples in the
instructions for line 11, earlier.

19. Nonrefundable Portion of Credit for Qualified
Sick and Family Leave Compensation for Leave
Taken After March 31, 2020, and Before April 1,
2021

18. Tax Adjustments

If you’re correcting the nonrefundable portion of the
credit for qualified sick and family leave compensation for
leave taken after March 31, 2020, and before April 1,
2021, that you reported on Form CT-1, line 16, enter the
total corrected amount from Worksheet 1, Step 2, line 2j,
in column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. For more information
about the credit for qualified sick and family leave
compensation, go to IRS.gov/PLC.

Don’t enter an amount on line 18 unless you need to
correct any current year adjustments reported on Form
CT-1, line 14. However, if you need to correct sick pay
adjustments for prior years reported on Form CT-1,
line 14, include the corrections in the calculations of Form
CT-1 X, lines 13–17.
Enter the corrected amount for tax adjustments in
column 1. Enter the originally reported or previously
corrected current year amount from Form CT-1, line 14, in
column 2. In column 3, enter the difference between
columns 1 and 2.
line 18 (column 1)
- line 18 (column 2)
line 18 (column 3)

Instructions for Form CT-1 X (Rev. 4-2025)

Generally, the period of limitations for correcting
the nonrefundable portion of credit for qualified
CAUTION sick and family leave compensation paid in 2020
expired on February 29, 2024, for most employers.
Generally, the period of limitations for correcting the
nonrefundable portion of credit for qualified sick and
family leave compensation paid in 2021 expired on
February 28, 2025, for most employers. For more
information about the period of limitations, see Is There a
Deadline for Filing Form CT-1 X, earlier.

!

Copy the amount in column 3 to column 4. However, to
properly show the amount as a credit or balance due item,
enter a positive number in column 3 as a negative number
in column 4 or a negative number in column 3 as a
positive number in column 4.

13

Adjustments to the nonrefundable portion of the

TIP credit for qualified sick and family leave

compensation for leave taken after March 31,
2020, and before April 1, 2021, are reported on Form CT-1
X, line 19, and adjustments to the refundable portion of
the credit are reported on Form CT-1 X, line 24.
Adjustments to qualified sick leave compensation and
qualified family leave compensation for leave taken after
March 31, 2020, and before April 1, 2021, are reported on
Form CT-1 X, lines 27 and 29, respectively. Adjustments
to qualified health plan expenses allocable to qualified
sick leave compensation and qualified family leave
compensation for leave taken after March 31, 2020, and
before April 1, 2021, are reported on Form CT-1 X, lines
28 and 30, respectively. For corrections to 2020 Form
CT-1, line 16, if the period of limitations is still open, the
credit for qualified sick and family leave compensation is
only available for compensation paid with respect to leave
taken after March 31, 2020, and before January 1, 2021.
For corrections to 2021, 2022, or 2023 Form CT-1, line 16,
the credit for qualified sick and family leave compensation
is only available for compensation paid in 2021, 2022, or
2023 with respect to any leave taken after March 31,
2020, and before April 1, 2021. If you're correcting a year
before 2020 because the period of limitations is still open,
don't enter any amount on line 19. If you claimed the credit
for qualified sick and family leave compensation for leave
taken after March 31, 2020, and before April 1, 2021, on
your original Form CT-1, and you make any corrections on
Form CT-1 X for the year to amounts used to figure this
credit, you’ll need to refigure the amount of the credit
using Worksheet 1. You’ll also use this worksheet to figure
this credit if you’re claiming the credit for the first time on
Form CT-1 X. For more information about the credit for
qualified sick and family leave compensation, go to
IRS.gov/PLC.
Example—Nonrefundable portion of credit for
qualified sick and family leave compensation
increased. You originally reported a $1,000
nonrefundable portion of credit for qualified sick and
family leave compensation on your 2021 Form CT-1,
line 16, but later determined that you understated qualified
sick leave compensation eligible for the credit. If your
period of limitations is still open, use Worksheet 1 to
refigure the correct nonrefundable portion of the credit for
qualified sick and family leave compensation and you
determine that the correct credit is now $2,000. To correct
the error, figure the difference on Form CT-1 X as shown.
Column 1 (corrected amount)
Column 2 (Form CT-1, line 16)
Column 3 (difference)

2,000.00
- 1,000.00
1,000.00

To properly show the credit increase as a reduction to
your balance, enter the positive number in column 3 as a
negative number in column 4. Here is how you would
enter the numbers on Form CT-1 X, line 19.

14

Column 1
(corrected
amount)
2,000.00

Column 2
(Form CT-1,
line 16)
1,000.00

Column 3
(difference)

Column 4
(tax correction)

1,000.00

-1,000.00

Be sure to explain the reasons for this correction on
line 43.

20b. Nonrefundable Portion of Credit for
Qualified Sick and Family Leave Compensation
for Leave Taken After March 31, 2021, and
Before October 1, 2021
Generally, the period of limitations for correcting
the nonrefundable portion of credit for qualified
CAUTION sick and family leave compensation paid in 2021
expired on February 28, 2025, for most employers. For
more information about the period of limitations, see Is
There a Deadline for Filing Form CT-1 X, earlier.

!

If you’re correcting the nonrefundable portion of the
credit for qualified sick and family leave compensation for
leave taken after March 31, 2021, and before October 1,
2021, that you reported on Form CT-1, line 17b, enter the
total corrected amount from Worksheet 2, Step 2, line 2r,
in column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. For more information
about the credit for qualified sick and family leave
compensation, go to IRS.gov/PLC.
For corrections to 2021, 2022, or 2023 Form CT-1,
line 17b, the credit for qualified sick and family leave
compensation is only available for compensation paid in
2021, 2022, or 2023 with respect to leave taken after
March 31, 2021, and before October 1, 2021. If you're
correcting a year before 2021 because the period of
limitations is still open, don't enter any amount on line 20b.
Copy the amount in column 3 to column 4. However, to
properly show the amount as a credit or balance due item,
enter a positive number in column 3 as a negative number
in column 4 or a negative number in column 3 as a
positive number in column 4. For an example of how to
report amounts in columns 1–4 for an employment tax
credit, see the instructions for line 19, earlier.
Be sure to explain the reasons for this correction on
line 43.

20c. Nonrefundable Portion of COBRA Premium
Assistance Credit
COBRA premium assistance was available for periods of
coverage beginning on or after April 1, 2021, through
periods of coverage beginning on or before September
30, 2021. For more information, see Credit for COBRA
premium assistance payments is limited to periods of
coverage beginning on or after April 1, 2021, through
periods of coverage beginning on or before September
30, 2021 under Reminders, earlier.

Instructions for Form CT-1 X (Rev. 4-2025)

Premium payees that receive an election from an

TIP assistance eligible individual are entitled to the

COBRA premium assistance credit for premiums
not paid during the quarter in which the election is
received. See Notice 2021-31 for more information.
If you’re correcting the nonrefundable portion of the
COBRA premium assistance credit that you reported on
Form CT-1, line 17c, enter the total corrected amount from
Worksheet 3, Step 2, line 2g, in column 1. In column 2,
enter the amount you originally reported or as previously
corrected. In column 3, enter the difference between
columns 1 and 2.
Copy the amount in column 3 to column 4. However, to
properly show the amount as a credit or balance due item,
enter a positive number in column 3 as a negative number
in column 4 or a negative number in column 3 as a
positive number in column 4. For an example of how to
report amounts in columns 1–4 for an employment tax
credit, see the instructions for line 19, earlier.
Be sure to explain the reasons for this correction on
line 43.

20d. Number of Individuals Provided COBRA
Premium Assistance

If you’re correcting the number of individuals provided
COBRA premium assistance that you reported on Form
CT-1, line 17d, enter the total corrected amount in column
1. In column 2, enter the amount you originally reported or
as previously corrected. In column 3, enter the difference
between columns 1 and 2.
Be sure to explain the reasons for this correction on
line 43.

21. Subtotal

Combine the amounts from column 4 on lines 6–20c and
enter the result on line 21.
Example. You entered “-500.00” in column 4 of line 6,
“-100.00” in column 4 of line 7, and “1,400.00” in column 4
of line 18. Combine these amounts and enter “800.00” in
column 4 of line 21.
Line 6
Line 7
Line 18
Line 21

-500.00
-100.00
+ 1,400.00
800.00

24. Refundable Portion of Credit for Qualified
Sick and Family Leave Compensation for Leave
Taken After March 31, 2020, and Before April 1,
2021
Generally, the period of limitations for correcting
the refundable portion of credit for qualified sick
CAUTION and family leave compensation paid in 2020
expired on February 29, 2024, for most employers.
Generally, the period of limitations for correcting the
refundable portion of credit for qualified sick and family
leave compensation paid in 2021 expired on February 28,

!

Instructions for Form CT-1 X (Rev. 4-2025)

2025, for most employers. For more information about the
period of limitations, see Is There a Deadline for Filing
Form CT-1 X, earlier.
If you’re correcting the refundable portion of the credit
for qualified sick and family leave compensation for leave
taken after March 31, 2020, and before April 1, 2021, that
you reported on Form CT-1, line 23, enter the total
corrected amount from Worksheet 1, Step 2, line 2k, in
column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. For more information
about the credit for qualified sick and family leave
compensation, go to IRS.gov/PLC.
For corrections to 2020 Form CT-1, line 23, if the period
of limitations is still open, the credit for qualified sick and
family leave compensation is only available for
compensation paid with respect to leave taken after March
31, 2020, and before January 1, 2021. For corrections to
2021, 2022, or 2023 Form CT-1, line 23, the credit for
qualified sick and family leave compensation is only
available for compensation paid in 2021, 2022, or 2023
with respect to any leave taken after March 31, 2020, and
before April 1, 2021. If you're correcting a year before
2020 because the period of limitations is still open, don't
enter any amount on line 24.
Copy the amount in column 3 to column 4. However, to
properly show the amount as a credit or balance due item,
enter a positive number in column 3 as a negative number
in column 4 or a negative number in column 3 as a
positive number in column 4. For an example of how to
report amounts in columns 1–4 for an employment tax
credit, see the instructions for line 19, earlier.
Be sure to explain the reasons for this correction on
line 43.

25b. Refundable Portion of Credit for Qualified
Sick and Family Leave Compensation for Leave
Taken After March 31, 2021, and Before October
1, 2021
Generally, the period of limitations for correcting
the refundable portion of credit for qualified sick
CAUTION and family leave compensation paid in 2021
expired on February 28, 2025, for most employers. For
more information about the period of limitations, see Is
There a Deadline for Filing Form CT-1 X, earlier.

!

If you’re correcting the refundable portion of the credit
for qualified sick and family leave compensation for leave
taken after March 31, 2021, and before October 1, 2021,
that you reported on Form CT-1, line 24b, enter the total
corrected amount from Worksheet 2, Step 2, line 2s, in
column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. For more information
about the credit for qualified sick and family leave
compensation, go to IRS.gov/PLC.
For corrections to 2021, 2022, or 2023 Form CT-1,
line 24b, the credit for qualified sick and family leave
compensation is only available for compensation paid in
2021, 2022, or 2023 with respect to leave taken after
March 31, 2021, and before October 1, 2021. If you're
15

correcting a year before 2021 because the period of
limitations is still open, don't enter any amount on line 25b.
Copy the amount in column 3 to column 4. However, to
properly show the amount as a credit or balance due item,
enter a positive number in column 3 as a negative number
in column 4 or a negative number in column 3 as a
positive number in column 4. For an example of how to
report amounts in columns 1–4 for an employment tax
credit, see the instructions for line 19, earlier.
Be sure to explain the reasons for this correction on
line 43.

25c. Refundable Portion of COBRA Premium
Assistance Credit

COBRA premium assistance was available for periods of
coverage beginning on or after April 1, 2021, through
periods of coverage beginning on or before September
30, 2021. For more information, see Credit for COBRA
premium assistance payments is limited to periods of
coverage beginning on or after April 1, 2021, through
periods of coverage beginning on or before September
30, 2021 under Reminders, earlier.

If you’re correcting the refundable portion of the
COBRA premium assistance credit that you reported on
Form CT-1, line 24c, enter the total corrected amount from
Worksheet 3, Step 2, line 2h, in column 1. In column 2,
enter the amount you originally reported or as previously
corrected. In column 3, enter the difference between
columns 1 and 2.
Copy the amount in column 3 to column 4. However, to
properly show the amount as a credit or balance due item,
enter a positive number in column 3 as a negative number
in column 4 or a negative number in column 3 as a
positive number in column 4. For an example of how to
report amounts in columns 1–4 for an employment tax
credit, see the instructions for line 19, earlier.
Be sure to explain the reasons for this correction on
line 43.

26. Total

Combine the amounts from column 4 on lines 21–25c and
enter the result on line 26.
Your credit. If the amount entered on line 26 is less than
zero, for example, “-115.00,” you have a credit because
you overreported your RRTA taxes.
• If you checked the box on line 1, include this amount on
Form CT-1, line 16 (“Total railroad retirement tax
deposits”), for the year during which you filed Form CT-1
X. Don’t make any changes to your Record of Railroad
Retirement Tax Liability in Part II of Form CT-1 or on Form
945-A, unless you were assessed an FTD penalty. For
more information, see the Instructions for Form 945-A.
The amounts reported on the record should reflect your
actual tax liability for the period.
• If you checked the box on line 2, you’re filing a claim for
refund or abatement of the amount shown.
If your credit is less than $1, we will send a refund or
apply it to your next return only if you ask us in writing to
do so.
16

Amount you owe. If the amount entered on line 26 is a
positive number, you must pay the amount you owe by
the time you file Form CT-1 X. You may not use any
credit that you show on another Form CT-1 X to pay the
amount you owe, even if you filed for the amount you owe
and the credit at the same time.
If you owe tax and are filing a timely Form CT-1 X, don’t
file an amended Form 945-A unless you were assessed
an FTD penalty caused by an incorrect, incomplete, or
missing Form 945-A. Don’t include the tax increase
reported on Form CT-1 X on any amended Form 945-A
you file.
If you owe tax and are filing a late Form CT-1 X, that is,
after the due date for Form CT-1 for the period in which
you discovered the error, you must file an amended Form
945-A with the Form CT-1 X. Otherwise, the IRS may
assess an “averaged” FTD penalty. The total tax reported
on Form 945-A, line M, must match the corrected tax
(Form CT-1, line 15 (line 19 for tax years 2020–2023),
combined with any correction reported on Form CT-1 X,
line 21) for the year, less any previous abatements and
interest-free tax assessments.
Payment methods. You may pay the amount you owe
on line 26 electronically using the Electronic Federal Tax
Payment System (EFTPS) or by a check or money order.
• The preferred method of payment is EFTPS. For more
information, go to EFTPS.gov or call 800-555-4477. To
contact EFTPS using Telecommunications Relay Services
(TRS) for people who are deaf, hard of hearing, or have a
speech disability, dial 711 and then provide the TRS
assistant the 800-555-4477 number above or
800-733-4829. Additional information about EFTPS is also
available in Pub. 966.
• If you pay by check or money order, make it payable to
“United States Treasury.” On your check or money order,
be sure to write your EIN, “Form CT-1 X,” and the year
corrected.
You don’t have to pay if the amount you owe is less than
$1.

Lines 27–30 and 33–38

For lines 27–30 and 33–38, you’ll only enter amounts in
columns 1, 2, and 3. These lines don’t have an entry
space for column 4 because these adjustments don’t
directly result in an increase or decrease to your tax. The
amounts entered on lines 27–30 and 33–38 are amounts
that you use on Worksheets 1–3, as applicable, to figure
your credits. If you reported an incorrect amount on lines
30–33 and 36–41 on your original Form CT-1, then you’ll
use lines 27–30 and 33–38 of Form CT-1 X to report the
correction. You’ll also use these lines to report amounts if
you’re claiming any credits for the first time on Form CT-1
X. Use Worksheets 1–3, as applicable, to refigure your
credits based on the corrected amounts reported in
column 1. Be sure to explain the reasons for your
corrections to lines 27–30 and 33–38 on line 43.

Instructions for Form CT-1 X (Rev. 4-2025)

27. Qualified Sick Leave Compensation for
Leave Taken After March 31, 2020, and Before
April 1, 2021

29. Qualified Family Leave Compensation for
Leave Taken After March 31, 2020, and Before
April 1, 2021

Generally, the period of limitations for correcting
qualified sick leave compensation paid in 2020
CAUTION expired on February 29, 2024, for most
employers. Generally, the period of limitations for
correcting qualified sick leave compensation paid in 2021
expired on February 28, 2025, for most employers. For
more information about the period of limitations, see Is
There a Deadline for Filing Form CT-1 X, earlier.

Generally, the period of limitations for correcting
qualified family leave compensation paid in 2020
CAUTION expired on February 29, 2024, for most
employers. Generally, the period of limitations for
correcting qualified family leave compensation paid in
2021 expired on February 28 2025, for most employers.
For more information about the period of limitations, see Is
There a Deadline for Filing Form CT-1 X, earlier.

If you’re correcting the qualified sick leave
compensation for leave taken after March 31, 2020, and
before April 1, 2021, that you reported on Form CT-1,
line 30, enter the total corrected amount for all employees
in column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. Qualified sick leave
compensation reported on this line is compensation
(determined without regard to the exclusions under
section 3231(e)(1)) paid under the Emergency Paid Sick
Leave Act (EPSLA) as enacted under the FFCRA and as
amended by the COVID-related Tax Relief Act of 2020.
Enter the corrected amount from column 1 on Worksheet
1, Step 2, line 2a.

If you’re correcting the qualified family leave
compensation for leave taken after March 31, 2020, and
before April 1, 2021, you reported on Form CT-1, line 32,
enter the total corrected amount for all employees in
column 1. In column 2, enter the amount you originally
reported or as previously corrected. In column 3, enter the
difference between columns 1 and 2. Qualified family
leave compensation reported on this line is compensation
(determined without regard to the exclusions under
section 3231(e)(1)) paid under the Emergency Family and
Medical Leave Expansion Act (Expanded FMLA) as
enacted under the FFCRA and as amended by the
COVID-related Tax Relief Act of 2020. Enter the corrected
amount from column 1 on Worksheet 1, Step 2, line 2e.

Be sure to explain the reasons for this correction on
line 43.

Be sure to explain the reasons for this correction on
line 43.

28. Qualified Health Plan Expenses Allocable to
Qualified Sick Leave Compensation for Leave
Taken After March 31, 2020, and Before April 1,
2021

30. Qualified Health Plan Expenses Allocable to
Qualified Family Leave Compensation for Leave
Taken After March 31, 2020, and Before April 1,
2021

Generally, the period of limitations for correcting
qualified health plan expenses allocable to
CAUTION qualified sick leave compensation paid in 2020
expired on February 29, 2024, for most employers.
Generally, the period of limitations for correcting qualified
health plan expenses allocable to qualified sick leave
compensation paid in 2021 expired on February 28, 2025,
for most employers. For more information about the period
of limitations, see Is There a Deadline for Filing Form CT-1
X, earlier.

Generally, the period of limitations for correcting
qualified health plan expenses allocable to
CAUTION qualified family leave compensation paid in 2020
expired on February 29, 2024, for most employers.
Generally, the period of limitations for correcting qualified
health plan expenses allocable to qualified family leave
compensation paid in 2021 expired on February 28, 2025,
for most employers. For more information about the period
of limitations, see Is There a Deadline for Filing Form CT-1
X, earlier.

If you’re correcting the qualified health plan expenses
allocable to qualified sick leave compensation for leave
taken after March 31, 2020, and before April 1, 2021, that
you reported on Form CT-1, line 31, enter the total
corrected amount for all employees in column 1. In column
2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2. Enter the corrected amount
from column 1 on Worksheet 1, Step 2, line 2b.

If you’re correcting the qualified health plan expenses
allocable to qualified family leave compensation for leave
taken after March 31, 2020, and before April 1, 2021, that
you reported on Form CT-1, line 33, enter the total
corrected amount for all employees in column 1. In column
2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2. Enter the corrected amount
from column 1 on Worksheet 1, Step 2, line 2f.

Be sure to explain the reasons for this correction on
line 43.

Be sure to explain the reasons for this correction on
line 43.

!

!

Instructions for Form CT-1 X (Rev. 4-2025)

!

!

17

33. Qualified Sick Leave Compensation for
Leave Taken After March 31, 2021, and Before
October 1, 2021
Generally, the period of limitations for correcting
qualified sick leave compensation paid in 2021
CAUTION expired on February 28, 2025, for most
employers. For more information about the period of
limitations, see Is There a Deadline for Filing Form CT-1 X,
earlier.

!

If you’re correcting the qualified sick leave
compensation for leave taken after March 31, 2021, and
before October 1, 2021, that you reported on Form CT-1,
line 36, enter the total corrected amount in column 1. In
column 2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2. Qualified sick leave
compensation reported on this line is compensation
(determined without regard to the exclusions under
section 3231(e)(1)) paid under the EPSLA as enacted
under the FFCRA and amended for purposes of the ARP.
Enter the corrected amount from column 1 on Worksheet
2, Step 2, line 2a.
Be sure to explain the reasons for this correction on
line 43.

34. Qualified Health Plan Expenses Allocable to
Qualified Sick Leave Compensation for Leave
Taken After March 31, 2021, and Before October
1, 2021
Generally, the period of limitations for correcting
qualified health plan expenses allocable to
CAUTION qualified sick leave compensation paid in 2021
expired on February 28, 2025, for most employers. For
more information about the period of limitations, see Is
There a Deadline for Filing Form CT-1 X, earlier.

!

If you’re correcting the qualified health plan expenses
allocable to qualified sick leave compensation for leave
taken after March 31, 2021, and before October 1, 2021,
that you reported on Form CT-1, line 37, enter the total
corrected amount for all employees in column 1. In column
2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2. Enter the corrected amount
from column 1 on Worksheet 2, Step 2, line 2b.
Be sure to explain the reasons for this correction on
line 43.

35. Amounts Under Certain Collectively
Bargained Agreements Allocable to Qualified
Sick Leave Compensation for Leave Taken After
March 31, 2021, and Before October 1, 2021
Generally, the period of limitations for correcting
the amounts under certain collectively bargained
CAUTION agreements allocable to qualified sick leave
compensation paid in 2021 expired on February 28, 2025,
for most employers. For more information about the period
of limitations, see Is There a Deadline for Filing Form CT-1
X, earlier.

!

18

If you’re correcting the amounts under certain
collectively bargained agreements allocable to qualified
sick leave compensation for leave taken after March 31,
2021, and before October 1, 2021, that you reported on
Form CT-1, line 38, enter the total corrected amount for all
employees in column 1. In column 2, enter the amount you
originally reported or as previously corrected. In column 3,
enter the difference between columns 1 and 2. Enter the
corrected amount from column 1 on Worksheet 2, Step 2,
line 2c.
Be sure to explain the reasons for this correction on
line 43.

36. Qualified Family Leave Compensation for
Leave Taken After March 31, 2021, and Before
October 1, 2021
Generally, the period of limitations for correcting
qualified family leave compensation paid in 2021
CAUTION expired on February 28, 2025, for most
employers. For more information about the period of
limitations, see Is There a Deadline for Filing Form CT-1 X,
earlier.

!

If you’re correcting the qualified family leave
compensation for leave taken after March 31, 2021, and
before October 1, 2021, that you reported on Form CT-1,
line 39, enter the total corrected amount in column 1. In
column 2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2. Qualified family leave
compensation reported on this line is compensation
(determined without regard to the exclusions under
section 3231(e)(1)) paid under the Expanded FMLA as
enacted under the FFCRA and amended for purposes of
the ARP. Enter the corrected amount from column 1 on
Worksheet 2, Step 2, line 2g.
Be sure to explain the reasons for this correction on
line 43.

37. Qualified Health Plan Expenses Allocable to
Qualified Family Leave Compensation for Leave
Taken After March 31, 2021, and Before October
1, 2021
Generally, the period of limitations for correcting
qualified health plan expenses allocable to
CAUTION qualified family leave compensation paid in 2021
expired on February 28, 2025, for most employers. For
more information about the period of limitations, see Is
There a Deadline for Filing Form CT-1 X, earlier.

!

If you’re correcting the qualified health plan expenses
allocable to qualified family leave compensation for leave
taken after March 31, 2021, and before October 1, 2021,
that you reported on Form CT-1, line 40, enter the total
corrected amount for all employees in column 1. In column
2, enter the amount you originally reported or as
previously corrected. In column 3, enter the difference
between columns 1 and 2. Enter the corrected amount
from column 1 on Worksheet 2, Step 2, line 2h.
Be sure to explain the reasons for this correction on
line 43.
Instructions for Form CT-1 X (Rev. 4-2025)

38. Amounts Under Certain Collectively
Bargained Agreements Allocable to Qualified
Family Leave Compensation for Leave Taken
After March 31, 2021, and Before October 1,
2021
Generally, the period of limitations for correcting
the amounts under certain collectively bargained
CAUTION agreements allocable to qualified family leave
compensation paid in 2021 expired on February 28, 2025,
for most employers. For more information about the period
of limitations, see Is There a Deadline for Filing Form CT-1
X, earlier.

!

If you’re correcting the amounts under certain
collectively bargained agreements allocable to qualified
family leave compensation for leave taken after March 31,
2021, and before October 1, 2021, that you reported on
Form CT-1, line 41, enter the total corrected amount for all
employees in column 1. In column 2, enter the amount you
originally reported or as previously corrected. In column 3,
enter the difference between columns 1 and 2. Enter the
corrected amount from column 1 on Worksheet 2, Step 2,
line 2i.
Be sure to explain the reasons for this correction on
line 43.

Part 4: Explain Your Corrections for
the Calendar Year You’re Correcting
41. Corrections of Both Underreported and
Overreported Amounts

Check the box on line 41 if any corrections you entered on
lines 6–19, 20b–20d, 24, 25b, 25c, 27–30, or 33–38 in
column 3 reflect both underreported and overreported
amounts.
Example. If you had an increase to Tier 1 Employer
compensation of $15,000 for Nathan Smith and a
decrease to Tier 1 Employer compensation of $5,000 for
Leah Green, you would enter $10,000 on line 6, column 3.
That $10,000 represents the net change resulting from
corrections.
On line 43, you must explain the reasons for both the
$15,000 increase and the $5,000 decrease.

42. Did You Reclassify Any Workers?

Check the box on line 42 if you reclassified any workers to
be independent contractors or nonemployees. Also check
this box if the IRS (or you) determined that workers you
treated as independent contractors or nonemployees
should be classified as employees. On line 43, provide a
detailed reason why any worker was reclassified.
Return not filed because you didn’t treat any workers
as employees. If you didn’t previously file Form CT-1
because you mistakenly treated all workers as
independent contractors or nonemployees, file a Form
CT-1 for each delinquent year.
Write “Misclassified Employees” in bold letters
across the top margin of page 1 of each Form CT-1.
Complete Form CT-1 using the Instructions for Form CT-1.
Attach a Form CT-1 X to each Form CT-1. Complete the
Instructions for Form CT-1 X (Rev. 4-2025)

top of Form CT-1 X, including the date you discovered the
error, and provide a detailed explanation on line 43.

43. Explain Your Corrections

Treasury regulations require you to explain in detail the
grounds and facts relied upon to support each correction.
On line 43, describe in detail each correction you entered
in column 4 on lines 6–19, 20b–20d, 24, 25b, and 25c.
Also use line 43 to describe corrections made on lines 27–
30 and 33–38. If you need more space, attach additional
sheets, but be sure to write your name, EIN, “Form CT-1
X,” and the calendar year you’re correcting on the top of
each sheet.
You must describe the events that caused the
underreported or overreported amounts. Explanations
such as “RRTA compensation was overstated,”
“administrative/payroll errors were discovered,” or “taxes
were not withheld” are insufficient and may delay the
processing of your Form CT-1 X because the IRS may
need to ask for a more complete explanation.

Provide the following information in your explanation of
each correction.
• Form CT-1 X line number(s) affected.
• Date you discovered the error.
• Difference (amount of the error).
• Cause of the error.
You may report the information in paragraph form. The
following paragraph is an example.
“The $1,000 difference shown in column 3 of lines 6
and 7 was discovered on May 15, 2025, during an internal
payroll audit. We discovered that we included $1,000 of
compensation for one of our employees twice. This
correction removes the reported compensation that was
never paid.”

Part 5: Sign Here
You must complete all five pages of Form CT-1 X and sign
it on page 5. If you don’t sign, the processing of Form
CT-1 X will be delayed.
Who must sign Form CT-1 X? The following persons
are authorized to sign the return for each type of business
entity.
• Sole proprietorship—The individual who owns the
business.
• Corporation (including a limited liability company
(LLC) treated as a corporation)—The president, the
vice president, or other principal officer duly authorized to
sign.
• Partnership (including an LLC treated as a
partnership) or unincorporated organization—A
responsible and duly authorized partner, member, or
officer having knowledge of its affairs.
• Single-member LLC treated as a disregarded entity
for federal income tax purposes—The owner of the
LLC or a principal officer duly authorized to sign.
• Trust or estate—The fiduciary.
A duly authorized agent of the taxpayer may also sign
Form CT-1 X if a valid power of attorney has been filed.
Alternative signature method. Corporate officers or
duly authorized agents may sign Form CT-1 X by rubber
stamp, mechanical device, or computer software program.
19

For details and required documentation, see Rev. Proc.
2005-39, 2005-28 I.R.B. 82, available at IRS.gov/irb/
2005-28_IRB#RP-2005-39.

Paid Preparer Use Only

A paid preparer must sign Form CT-1 X and provide the
information in the Paid Preparer Use Only section of Part 5
if the preparer was paid to prepare Form CT-1 X and isn’t
an employee of the filing entity. Paid preparers must sign
paper returns with a manual signature. The preparer must
give the employer the return to file with the IRS and
include a copy of the return for the employer's records.
If you’re a paid preparer, write your Preparer Tax
Identification Number (PTIN) in the space provided.
Include your complete address. If you work for a firm, write
the firm's name and the EIN of the firm. You can apply for
a PTIN online or by filing Form W-12. For more information
about applying for a PTIN online, go to IRS.gov/PTIN. You
can’t use your PTIN in place of the EIN of the tax
preparation firm.
Generally, you’re not required to complete this section if
you’re filing the return as a reporting agent and have a
valid Form 8655 on file with the IRS. However, a reporting
agent must complete this section if the reporting agent
offered legal advice, for example, advising the client on
determining whether its workers are employees or
independent contractors for federal tax purposes.

Paperwork Reduction Act Notice. We ask for the
information on Form CT-1 X to carry out the Internal
Revenue laws of the United States. You’re required to give
us the information. We need it to ensure that you’re
complying with these laws and to allow us to figure and
collect the right amount of tax.
You're not required to provide the information requested
on a form that is subject to the Paperwork Reduction Act
unless the form displays a valid OMB control number.
Books or records relating to a form or its instructions must
be retained as long as their contents may become
material in the administration of any Internal Revenue law.
Generally, tax returns and return information are
confidential, as required by section 6103.
The time needed to complete and file Form CT-1 X will
vary depending on individual circumstances. The
estimated burden for employers filing Form CT-1 X is
approved under OMB control number 1545-0029 and is
included in the estimates shown in the Instructions for
Form 941.

How Can You Get Forms, Instructions,
and Publications From the IRS?
You can download or print some of the forms and
publications you may need at IRS.gov/Forms.
Otherwise, you can go to IRS.gov/OrderForms to
place an order and have forms mailed to you. The IRS will
process your order for forms and publications as soon as
possible. Don’t resubmit requests you’ve already sent us.
You can get forms and publications faster online.

20

Instructions for Form CT-1 X (Rev. 4-2025)

Worksheet 1. Adjusted Credit for Qualified Sick and Family Leave
Compensation for Leave Taken After March 31, 2020, and Before
April 1, 2021

Keep for Your Records

You must use this worksheet if you claimed the credit for qualified sick and family leave compensation for leave taken after March 31, 2020, and
before April 1, 2021, on your original Form CT-1 and you correct any amounts used to figure the credit for qualified sick and family leave
compensation for leave taken after March 31, 2020, and before April 1, 2021. You'll also use this worksheet to figure this credit if you're claiming it
for the first time on Form CT-1 X.
Step 1.

1a
1b
1c

Step 2.

2a
2a(i)
2a(ii)
2b
2c
2d
2e
2e(i)
2e(ii)
2f
2g
2h
2i
2j

2k

Figure the Tier 1 Employer Tax
Enter the amount from Form CT-1, line 1 (Tax Column), or, if corrected, enter the
amount from Form CT-1 X, line 6, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1a
Enter the amount from Form CT-1, line 8 (Tax Column), or, if corrected, enter the
amount from Form CT-1 X, line 13, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1b
Tier 1 Employer tax. Add lines 1a and 1b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure the credit for qualified sick and family leave compensation
Qualified sick leave compensation reported on Form CT-1, line 30, or, if corrected, the
amount from Form CT-1 X, line 27, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enter the amount, if any, included on line 2a that is compensation excluded from the
definition of compensation under section 3231(e)(1) . . . . . . . . . . . . . . . . . . . . . . . . .
Subtract line 2a(i) from line 2a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualified health plan expenses allocable to qualified sick leave compensation reported
on Form CT-1, line 31, or, if corrected, Form CT-1 X, line 28, column 1 . . . . . . . . . . . .
Tier 1 Employer Medicare tax on qualified sick leave compensation. Multiply line 2a(ii)
by 1.45% (0.0145) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Credit for qualified sick leave compensation. Add lines 2a, 2b, and 2c . . . . . . . . .
Qualified family leave compensation reported on Form CT-1, line 32, or, if corrected,
the amount from Form CT-1 X, line 29, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enter the amount, if any, included on line 2e that is compensation excluded from the
definition of compensation under section 3231(e)(1) . . . . . . . . . . . . . . . . . . . . . . . . .
Subtract line 2e(i) from line 2e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualified health plan expenses allocable to qualified family leave compensation
reported on Form CT-1, line 33, or, if corrected, the amount from Form CT-1 X, line 30,
column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tier 1 Employer Medicare tax on qualified family leave compensation. Multiply
line 2e(ii) by 1.45% (0.0145) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Credit for qualified family leave compensation. Add lines 2e, 2f, and 2g . . . . . . .
Credit for qualified sick and family leave compensation. Add lines 2d
and 2h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nonrefundable portion of credit for qualified sick and family leave
compensation for leave taken after March 31, 2020, and before April 1, 2021.
Enter the smaller of line 1c or line 2i. Enter this amount on Form CT-1 X, line 19,
column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Refundable portion of credit for qualified sick and family leave compensation
for leave taken after March 31, 2020, and before April 1, 2021. Subtract line 2j
from line 2i and enter this amount on Form CT-1 X, line 24, column 1 . . . . . . . . . . . . .

Instructions for Form CT-1 X (Rev. 4-2025)

1c

2a
2a(i)
2a(ii)
2b
2c

2d

2e
2e(i)
2e(ii)
2f
2g

2h
2i

2j
2k

21

Worksheet 2. Adjusted Credit for Qualified Sick and Family Leave
Compensation for Leave Taken After March 31, 2021, and Before
October 1, 2021

Keep for Your Records

You must use this worksheet if you claimed the credit for qualified sick and family leave compensation for leave taken after March 31, 2021, and before
October 1, 2021, on your original Form CT-1 and you correct any amounts used to figure the credit for qualified sick and family leave compensation for leave
taken after March 31, 2021, and before October 1, 2021. You'll also use this worksheet to figure this credit if you're claiming it for the first time on Form CT-1 X.
Step 1.

1a
1b
1c

Step 2.

22

Figure the Tier 1 Employer Medicare Tax
Enter the amount from Form CT-1, line 2 (Tax Column), or, if corrected, the amount from Form
CT-1 X, line 7, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1a
Enter the amount from Form CT-1, line 9 (Tax Column), or, if corrected, the amount from Form
CT-1 X, line 14, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1b
Tier 1 Employer Medicare tax. Add lines 1a and 1b . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure the credit for qualified sick and family leave compensation
Qualified sick leave compensation for leave taken after March 31, 2021, and before October 1,
2021, reported on Form CT-1, line 36, or, if corrected, the amount from Form CT-1 X, line 33,
column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2a(i) Enter the amount, if any, included on line 2a that is compensation excluded from the definition
of compensation under section 3231(e)(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2a(ii) Subtract line 2a(i) from line 2a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2a(iii) Enter the amount, if any, included on line 2a that was not included as compensation on Form
CT-1, lines 1, 4, 8, and 10, or, if corrected, on Form CT-1 X, lines 6, 9, 13, and 15, because the
qualified sick leave compensation was limited by the Tier 1 compensation base . . . . . . . . . . .
2a(iv) Subtract line 2a(iii) from line 2a(ii) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2b
Qualified health plan expenses allocable to qualified sick leave compensation taken after March
31, 2021, and before October 1, 2021, reported on Form CT-1, line 37, or, if corrected, the
amount from Form CT-1 X, line 34, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2c
Amounts under certain collectively bargained agreements allocable to qualified sick leave
compensation for leave taken after March 31, 2021, and before October 1, 2021, reported on
Form CT-1, line 38, or, if corrected, the amount from Form CT-1 X, line 35, column 1 . . . . . . .
2d
Tier 1 Employer tax on qualified sick leave compensation. Multiply line 2a(iv) by 6.2%
(0.062) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2e
Tier 1 Employer Medicare tax on qualified sick leave compensation. Multiply line 2a(ii) by 1.45%
(0.0145) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2f
Credit for qualified sick leave compensation. Add lines 2a, 2b, 2c, 2d, and 2e . . . . . . . . .
2g
Qualified family leave compensation for leave taken after March 31, 2021, and before October
1, 2021, reported on Form CT-1, line 39, or, if corrected, the amount from Form CT-1 X, line 36,
column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2g(i) Enter the amount, if any, included on line 2g that is compensation excluded from the definition
of compensation under section 3231(e)(1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2g(ii) Subtract line 2g(i) from line 2g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2g(iii) Enter the amount, if any, included on line 2g that was not included as compensation on Form
CT-1, lines 1, 4, 8, and 10, or, if corrected, on Form CT-1 X, lines 6, 9, 13, and 15, because the
qualified family leave compensation was limited by the Tier 1 compensation base . . . . . . . . .
2g(iv) Subtract line 2g(iii) from line 2g(ii) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2h
Qualified health plan expenses allocable to qualified family leave compensation taken after
March 31, 2021, and before October 1, 2021, reported on Form CT-1, line 40, or, if corrected,
the amount from Form CT-1 X, line 37, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2i
Amounts under certain collectively bargained agreements allocable to qualified family leave
compensation for leave taken after March 31, 2021, and before October 1, 2021, reported on
Form CT-1, line 41, or, if corrected, the amount from Form CT-1 X, line 38, column 1 . . . . . . .
2j
Tier 1 Employer tax on qualified family leave compensation. Multiply line 2g(iv) by 6.2%
(0.062) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2k
Tier 1 Employer Medicare tax on qualified family leave compensation. Multiply line 2g(ii) by
1.45% (0.0145) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2l
Credit for qualified family leave compensation. Add lines 2g, 2h, 2i, 2j, and 2k . . . . . . . . .
2m
Credit for qualified sick and family leave compensation. Add lines 2f and 2l . . . . . . . . . .
2n
Reserved for future use
2o
Enter any credit claimed under section 41 for increasing research activities with respect to any
compensation taken into account for the credit for qualified sick and family leave
compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2p
Reserved for future use
2q
Credit for qualified sick and family leave compensation after adjusting for other credits.
Subtract line 2o from line 2m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2r
Nonrefundable portion of credit for qualified sick and family leave compensation for
leave taken after March 31, 2021, and before October 1, 2021. Enter the smaller of line 1c
or line 2q. Enter this amount on Form CT-1 X, line 20b, column 1 . . . . . . . . . . . . . . . . . . . . .
2s
Refundable portion of credit for qualified sick and family leave compensation for leave
taken after March 31, 2021, and before October 1, 2021. Subtract line 2r from line 2q and
enter this amount on Form CT-1 X, line 25b, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1c

2a

2a
2a(i)
2a(ii)
2a(iii)
2a(iv)
2b
2c
2d
2e
2f
2g
2g(i)
2g(ii)
2g(iii)
2g(iv)
2h
2i
2j
2k
2l
2m

2o
2q
2r
2s

Instructions for Form CT-1 X (Rev. 4-2025)

Keep for Your Records

Worksheet 3. Adjusted COBRA Premium Assistance Credit

You must use this worksheet if you claimed the COBRA premium assistance credit on your original Form CT-1 and you correct any amounts used to figure the
COBRA premium assistance credit. You'll also use this worksheet to figure this credit if you're claiming it for the first time on Form CT-1 X.
Step 1.
1a

1b
1c
1d
Step 2.
2a

2b
2c

2d
2e
2f
2g
2h

Figure the Tier 1 Employer Medicare Tax
If you completed Worksheet 2 and you’re also claiming the COBRA premium assistance credit,
enter the amount from Worksheet 2, Step 1, line 1c. Otherwise, complete lines 1b–1d below
and then go to Step 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enter the amount from Form CT-1, line 2 (Tax Column), or, if corrected, the amount from Form
CT-1 X, line 7, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enter the amount from Form CT-1, line 9 (Tax Column), or, if corrected, the amount from Form
CT-1 X, line 14, column 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tier 1 Employer Medicare tax. Add lines 1b and 1c . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure the COBRA premium assistance credit
Enter the COBRA premium assistance that you provided for periods of coverage beginning on
or after April 1, 2021, through periods of coverage beginning on or before September 30,
2021 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enter the amount of the Tier 1 Employer Medicare tax from Step 1, line 1a, or, if applicable,
Step 1, line 1d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enter the amount of the nonrefundable portion of the credit for qualified sick and family leave
compensation for leave taken after March 31, 2021, and before October 1, 2021 (this amount
may come from Worksheet 2, Step 2, line 2r, in these instructions if you're correcting that credit
or you may need to enter the credit claimed on your original Form CT-1) . . . . . . . . . . . . . . .
Reserved for future use
Reserved for future use
Subtract line 2c from line 2b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nonrefundable portion of the COBRA premium assistance credit. Enter the smaller of
line 2a or line 2f. Enter this amount on Form CT-1 X, line 20c, column 1 . . . . . . . . . . . . . . . .
Refundable portion of the COBRA premium assistance credit. Subtract line 2g from
line 2a and enter this amount on Form CT-1 X, line 25c, column 1 . . . . . . . . . . . . . . . . . . .

Instructions for Form CT-1 X (Rev. 4-2025)

1a
1b
1c
1d

2a
2b

2c

2f
2g
2h

23