How to amend a tax return after you’ve filed

Mistakes happen. Here’s how to fix them.

Written byNancy Ashburn

Fact-checked byDavid Schepp

Red alarm clock and pencil eraser over a U.S. 1040 tax form marked with red checkmarks, Xs, and circled figures on a yellow background.

Clear up errors and file a corrected return.

Filing your taxes can be complicated, especially if you later realize you need to amend a tax return. Even if you think you did your taxes correctly and included every required form, mistakes still happen. Sometimes, new or updated information arrives after you file and changes what you originally reported. Knowing how to amend a tax return can help you get it fixed and move on.

Correcting a return isn’t uncommon. For the 2020 tax year, the Internal Revenue Service received nearly 116 million tax returns, and about 2.8%—roughly 3.3 million—were later amended.

Key Points

Mathematical errors and discrepancies between forms the IRS received (such as a W-2) and what you reported on your return are often caught automatically.
Form 1040-X is the document used to correct a return that’s been filed.
You typically have up to three years from your original filing date to file an amended return.
If your original return was e-filed, your amendment can often be filed electronically as well.

Reasons to amend your tax return

Sometimes the IRS discovers a math error or a mismatch between what you reported on your return and the information already on file. For example, if your W-2 said your wages were $48,250 and you reported $48,520, the IRS will usually catch the error and make the change for you. When it does, the IRS generally notifies you that it has made the correction and that no further action is needed on your part.

How long should you keep old tax returns?

The IRS generally recommends keeping copies of your federal tax returns and supporting documents for at least three years after you file. That time frame reflects how long the IRS generally has to review or question a return and the period during which you can file an amended return.

If key information on your Form 1040 changes, you’ll usually need to file an amended return. Common reasons to amend your return include changes to your:

Filing status (for example, switching to a joint return after originally filing separately)
Income (for example, freelance or side-hustle income that wasn’t included)
Deductions (for example, education expenses you later realized you could deduct)
Credits (for example, the earned income tax credit, if you later realized you qualified)
Dependents (for example, realizing a child no longer qualifies as a dependent)
Amount of tax due (for example, after correcting a deduction or credit)

If any of these situations apply, the next step is to fill out Form 1040-X.

Completing Form 1040-X

Form 1040-X carries over all of the information from your original Form 1040 that hasn’t changed. Only the items you’re changing are updated.

It can save time if you have your original Form 1040 handy. If it was filed electronically, the tax software or online tax program you used will usually allow you to prepare and submit an amended return.

Form 1040-X includes these sections:

General information. Enter the tax year you’re amending, along with your name, address, and other identifying information. Select the filing status as shown on your previous return, unless the amendment changes it.
Column A (as originally reported). Enter the amounts from the most recently processed version of your return, whether that’s your original filing or a version the IRS later corrected.
Column B (increase or decrease). This column shows the amount of each change, which you’ll explain in Part II.
Column C (correct amount). Add or subtract the amount in Column B to or from Column A. If no changes were made in Column B, enter the amount from Column A.
Part I dependents. Complete this section only if you’re changing information about your dependents.
Part II explanation of changes. Explain why you’re filing Form 1040-X and attach documentation that supports the changes.
Sign your return. If you’re amending a joint return, your spouse must also sign.

How to file your amended tax return

If you filed your original tax return on paper, you’ll also file a paper amended return. If you filed electronically, the tax software or online tax program you used usually allows you to amend returns from the past three tax years and submit Form 1040-X electronically (you’ll also need to include Form 8879, the e-file signature authorization). If you need to amend a return more than once, the IRS generally allows up to three amended returns for the same tax year.

When is your amended return due?

You generally have up to three years to amend your tax return. Even if you filed early, the three-year clock normally starts on the April tax deadline (typically April 15). If you paid tax after filing, you can file an amended return up to two years after the payment date, even if your original filing date was earlier. Special rules apply in certain situations, such as military service in a combat zone or claiming a foreign tax credit.

Paying tax or getting a refund from your 1040-X

If you owe additional tax with your amended return, you can submit a payment using Form 1040-V. Any interest or penalties due will be calculated by the IRS and billed separately. If your electronically filed amendment results in a refund, follow your tax software or website’s guidance for refund options.

The bottom line

Realizing you made an error on a tax return after filing is common, and filing an amended return is how you address it. Act promptly to help ensure you don’t miss the deadline for fixing your return. Having your original Form 1040—or access to the tax software or online service you used—can make the process easier. If you filed a state income tax return, it may also need to be amended.

Amending a tax return can take time, particularly if you need to gather additional documentation. Taxpayers spend an average of about nine hours preparing an amended return, according to the IRS. Some also incur out-of-pocket costs for tax preparation help, with the IRS estimating an average cost of about $200 in 2024.

If you’re unsure whether you need to file an amended return, the IRS website has an online tool to help you decide. You can usually check the status of an amended return about three weeks after filing, although processing can take up to 16 weeks.

References

Should I File an Amended Return? | irs.gov
Instructions for Form 1040-X | irs.gov
Where’s My Amended Return? | irs.gov
[PDF] Form 1040-X | irs.gov

This article was most recently revised and updated by Nancy AshburnThis article was most recently revised and updated by David Schepp