# Form 1040-X: how to fill it out, what to attach and where to send it

Source: https://taxrefunddesk.com/amended-returns/form-1040-x-how-to
Publisher: Tax Refund Desk (taxrefunddesk.com), independent editorial site
Topic: Amended Returns
Last updated: 2026-09-19

> Form 1040-X is the IRS form for correcting a Form 1040, 1040-SR or 1040-NR you already filed. You enter the original figures in Column A, the change in Column B and the corrected figures in Column C, explain each change in Part II, attach only the schedules that changed, and e-file or mail it. Use one 1040-X per tax year.

## Key facts

- Current instructions: Form 1040-X instructions, revision December 2025
- Three columns: A = original, B = net change, C = corrected
- E-file: Through tax software; tax year 2021 and earlier must be mailed
- Paper mailing centers: Austin TX, Ogden UT or Kansas City MO, by state
- Joint returns: Both spouses must sign

## What Form 1040-X is for

Form 1040-X, Amended U.S. Individual Income Tax Return, corrects a return that the IRS already has on file. It is used for tax returns originally filed on Form 1040, 1040-SR or 1040-NR, and it works for changes that raise your refund, reduce it, or create a balance due. The current 1040-X instructions are the December 2025 revision.

The 1040-X form is not a full second return. It records only what changed and why, and the IRS matches it to the original. For the bigger picture on whether you should amend at all, start with our [amended return guide](https://taxrefunddesk.com/amended-returns).

## Before you start: what to have on hand

- A copy of the original return exactly as filed, or as the IRS last adjusted it if you received a notice such as a CP12.
- The document behind the change: a Form W-2c, a corrected 1099, a Form 1098-T, receipts, or a dependent's records.
- Any schedules or forms affected by the change, already recalculated (for example Schedule 1, Schedule 8812 or Schedule EIC).
- Your Identity Protection PIN, if the IRS issued one to you, your spouse or a dependent. All six digits must be entered.
- Bank routing and account numbers if you will e-file and want the refund by direct deposit.

> **Use the adjusted figures if the IRS already changed your return:** If the IRS changed your original return and mailed you a notice, Column A must show the figures as the IRS adjusted them, not the numbers you first filed. Your account transcript lists the adjusted amounts.

## 1040-X instructions for Columns A, B and C

The heart of Form 1040-X is its three columns. **Column A** holds the amounts from your original return, or as previously adjusted by the IRS. **Column B** holds the net increase or decrease for each line you are changing, with decreases shown in parentheses. **Column C** is Column A plus or minus Column B.

Lines you are not changing still get Column A and Column C figures, which will be the same. Leave Column B blank for those lines. Key lines include line 1 (adjusted gross income), line 2 (itemized or standard deduction), line 5 (taxable income), line 6 (tax) and line 12 (withholding).

### Worked example: a corrected W-2 with more withholding

Suppose your employer issues a W-2c showing $4,600 of federal income tax withheld instead of the $4,100 on your original W-2. Your tax of $3,200 does not change, and your original return produced a $900 refund, which you already received. The example numbers below are illustrative.

| Line | Column A (original) | Column B (change) | Column C (corrected) |
| --- | --- | --- | --- |
| 11 Total tax | $3,200 | blank | $3,200 |
| 12 Withholding | $4,100 | +$500 | $4,600 |
| 17 Total payments | $4,100 | +$500 | $4,600 |
| Overpayment shown on original return |  |  | $900 |
| Additional refund due |  |  | $500 |

Example Form 1040-X entries for extra withholding (illustrative figures)

The form subtracts the overpayment already shown on the original return from the corrected payments ($4,600 minus $900 is $3,700), then compares that with the corrected tax of $3,200. The $500 difference is the extra refund. You would attach the W-2c, because it shows the added withholding.

## Explaining the changes in Part II

Part II, Explanation of Changes, tells the IRS employee who reviews your 1040-X what you changed and why. A vague line such as "corrected return" invites a letter asking for more. Name the line, the amount, the reason and the document you are attaching.

- Weak: "Forgot some income."
- Strong: "Line 1 increased by $1,850 for Form 1099-NEC income from a client, received after the original return was filed. Schedule C and Schedule SE attached."
- Strong: "Line 12 increased by $500. Employer issued Form W-2c correcting federal withholding. W-2c attached."

Part I, Dependents, is completed only if you are adding or changing dependents, and Part III is used for direct deposit on an e-filed 1040-X. If you are filing a carryback claim or amending for a deceased taxpayer, the instructions tell you to write "Carryback Claim" or "Deceased" with the date of death across the top.

## What to attach to Form 1040-X

Attach only what changed. The IRS asks for any schedule or form that the change affects, and for new or corrected W-2, W-2c and 1099-R forms that show more tax withheld. You do not send a full copy of the original return.

Missing attachments are one of the reasons an amended return goes past 12 weeks, because the IRS has to write to you and wait for a reply. Our page on [amended return processing time](https://taxrefunddesk.com/amended-returns/amended-return-processing-time) lists the other causes.

## Can I e-file Form 1040-X?

Yes, for recent tax years. You can e-file Form 1040-X through tax software, and the IRS says returns for tax year 2021 and earlier must be mailed on paper. You can e-file up to three amended returns for the same tax year; a fourth is rejected. If a paid preparer transmits it, you also sign Form 8879.

One catch: if you filed the original return on paper during the current processing year, the IRS says the amendment must also be on paper. Our page on how to [amend a tax return online](https://taxrefunddesk.com/amended-returns/amend-tax-return-online) explains the free options and when software support ends.

## 1040-X mailing address by state

Paper 1040-X forms go to one of three IRS centers based on where you live, per the December 2025 instructions. Check the Where To File table in the current instructions before mailing, because the IRS can change addresses between revisions.

| If you live in | Mail to |
| --- | --- |
| AL, AR, FL, GA, LA, MS, OK, TX | Department of the Treasury, Internal Revenue Service, Austin, TX 73301-0052 |
| AK, AZ, CA, CO, HI, ID, IA, KS, MI, MT, NE, NV, NM, ND, OH, OR, SD, UT, WA, WY | Department of the Treasury, Internal Revenue Service, Ogden, UT 84201-0052 |
| CT, DE, DC, IL, IN, KY, ME, MD, MA, MN, MO, NH, NJ, NY, NC, PA, RI, SC, TN, VT, VA, WV, WI | Department of the Treasury, Internal Revenue Service, Kansas City, MO 64999-0052 |

Where to mail a paper Form 1040-X (Rev. December 2025)

Different addresses apply to Form 1040-NR filers, taxpayers with foreign addresses, dual-status aliens and some responses to IRS notices; the instructions list those separately. Mail each tax year's 1040-X in its own envelope, and consider a mailing method that gives you proof of the send date.

## How to file a tax return amendment and follow it up

Sign and date the form. On a joint amended return, both spouses must sign, and an e-filed joint 1040-X must carry each spouse's PIN and IP PIN if one was issued. An unsigned 1040-X is sent back or held.

About 3 weeks after you submit, check [Where's My Amended Return](https://taxrefunddesk.com/amended-returns/wheres-my-amended-return) with your Social Security number, date of birth and ZIP code. For line-by-line detail on what the IRS posted, request an account transcript; our [amended return transcript](https://taxrefunddesk.com/amended-returns/amended-return-transcript) page decodes the TC 971, 977 and 846 entries.

If you also filed a state return, your state may need its own amended form. The IRS notes that a federal change can affect state tax, but it does not file the state amendment for you.

## Step by step

1. **Gather records.** Collect the original return as filed or as adjusted by the IRS, and the document that caused the change.
2. **Recalculate affected schedules.** Redo any schedule or form the change affects, such as Schedule 1 or Schedule 8812.
3. **Complete Columns A, B and C.** Enter original figures in Column A, the net change in Column B and corrected figures in Column C.
4. **Explain the changes.** In Part II, name each changed line, the amount, the reason and the attached document.
5. **Attach supporting forms.** Include changed schedules and any new or corrected W-2, W-2c or 1099-R forms that show withholding.
6. **Sign and submit.** Sign (both spouses on a joint return), then e-file through software or mail to the address for your state.
7. **Track the status.** Check Where's My Amended Return about 3 weeks after submitting.

## Common questions

### Do I need to file a separate 1040-X for each year?

Yes. Each Form 1040-X covers one tax year. If the same mistake affected 2023 and 2024, file two forms and mail them in separate envelopes if filing on paper.

### Should I send the 1040-X to the same address as my original return?

Not necessarily. Paper 1040-X forms go to the Austin, Ogden or Kansas City address for your state listed in the 1040-X instructions, which can differ from where Form 1040 is mailed.

### What do I put in Column B if a number went down?

Enter the decrease in parentheses in Column B, then subtract it from Column A to get Column C. Leave Column B blank on lines that did not change.

### Can I amend just my state return without Form 1040-X?

Yes, if the change affects only your state return. Form 1040-X is only for federal changes; your state has its own amended return process.

### Do I include my IP PIN on Form 1040-X?

Yes. Anyone on the return who has an Identity Protection PIN must enter it on the 1040-X, and an e-filed amended return is rejected if a required IP PIN is missing or wrong.

### Do I need to sign a paper 1040-X in ink?

Sign the paper form yourself, and on a joint amended return both spouses must sign. An unsigned 1040-X is treated as incomplete and delays processing.

## Sources

- [Instructions for Form 1040-X (Rev. December 2025)](https://www.irs.gov/instructions/i1040x)
- [IRS, File an amended return](https://www.irs.gov/filing/file-an-amended-return)
- [IRS Tax Topic 308, Amended returns](https://www.irs.gov/taxtopics/tc308)
- [IRS, Amended return frequently asked questions](https://www.irs.gov/filing/amended-return-frequently-asked-questions)