How Should You — Instruction 943-X — Instructions for Form

Use a Separate Form 943-X for Each Year You’re Correcting Use a separate Form 943-X for each Form 943 that you’re correcting. For example, if you found errors on your Forms 943 for 2024 and 2025, file one Form 943-X to correct the 2024 Form 943, and file a second Form 943-X to correct the 2025 Form 943.

Employer Identification Number (EIN), Name, and Address Enter your EIN, 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 943, enter the corrected information and the IRS will update your address of record. Be sure to write your name, EIN, “Form 943-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 943 you’re correcting in the box at the top of page 1. Enter the same calendar year on pages 2, 3, 4, and 5, and on any attachments.

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 the error. If you’re reporting several errors you discovered at different times, enter the earliest date you discovered an error here. Report any subsequent dates and related errors on line 41.

Aggregate Return Filers Only If you’re filing an aggregate Form 943-X, check the appropriate box to identify yourself. An aggregate Form 943-X is a return that combines amounts from multiple

clients or customers (employers) onto a single Form 943-X.

Section 3504 Agent. Check this box if you’re a section 3504 agent filing an aggregate Form 943-X. You must attach Schedule R (Form 943) to your aggregate Form 943-X. For more information about section 3504 agents, see You may need to attach Schedule R (Form 943) to your Form 943-X , earlier, and section 16 of Pub. 15.

Certified Professional Employer Organization (CPEO). Check this box if you’re a CPEO filing an aggregate Form 943-X on behalf of your customers. You must attach Schedule R (Form 943) to your aggregate Form 943-X. For more information about CPEOs, see Certification program for professional employer organizations (PEOs) , earlier, and section 16 of Pub.15.

Other Third Party. If you’re filing an aggregate Form 943-X but you’re not a section 3504 agent or a CPEO, you must check this box. For example, a non-certified PEO filing an aggregate Form 943-X must check this box.

Must You Make an Entry on Each Line? You must provide all of the information requested at the top of Form 943-X, page 1. 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.

How Should You Report Negative Amounts? Form 943-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.

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 Form 943 for the year in which you discover the error),
Pay the amount shown on line 25 by the time you file Form 943-X,

How Should You Make Entries on Form 943-X? You can help the IRS process Form 943-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 943-X on page 5.
Staple multiple sheets in the upper-left corner.

Instructions for Form 943-X (Rev. 2-2026) 7

Enter the date you discovered the error, and
Explain in detail the grounds and facts relied upon to support the correction.

No correction will be eligible for interest-free treatment if any of the following apply.

The amounts underreported 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

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.