What is an amended tax return?

Fix major mistakes on old tax returns by filing an amended return.

Derek Silva


Derek Silva

Derek Silva

Senior Editor & Personal Finance Expert

Derek is a former senior editor and personal finance expert at Policygenius, where he specialized in financial data, taxes, estate planning, and investing. Previously, he was a staff writer at SmartAsset.

Updated June 18, 2021 | 6 min read

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An amended tax return allows you to fix mistakes on a federal income tax return that you’ve already filed. There is no penalty for filing a tax amendment, but you will have to pay late fees and interest if you owe any money to the Internal Revenue Service (IRS).

You should only amend your return if you made a major mistake, like if you used the incorrect filing status, forgot to include income, or didn’t claim the correct tax deductions or credits. You do not need to amend your return just for math errors because the IRS usually fixes them. It also isn’t necessary just because you forgot to attach a form or schedule. If the IRS finds errors in your return or needs a form that you forgot to include, it will send you a letter asking you to mail the document so they can finish processing your return.

Prior to 2019, you could only file an amended return by mailing a completed Form 1040-X to the correct IRS address. The IRS began allowing e-filing for 1040-X forms in 2019.

Key Takeaways

  • File an amended return if you made a big mistake, which doesn’t usually include math errors

  • All tax filers use the same Form 1040-X to amend a tax return

  • Unless you’re amending a 2019 tax return, you can’t file Form 1040-X electronically and must mail a physical copy to the IRS

  • The IRS only accepts amended returns for three years after the due date of the original tax return, including tax extensions you received

Should I amend my tax return?

You should file an amended federal return when there is a major mistake with the information you provided on your return, like if you forget to claim a tax credit. You generally don’t need to fill out an amendment for mathematical errors because the IRS commonly finds and corrects math errors without the tax filer needing to do anything. If there is a big mathematical error and you end up needing to return some of your tax refund or even pay a tax bill, the IRS will notify you with a letter. The IRS will also send a letter if it needs a form that’s missing from your return.

Here are a handful of situations when you should file an amended tax return:

  • Personal information, like your Social Security number, was incorrect on your return.

  • You used the wrong tax filing status, like filing head of household when you don’t qualify.

  • You claimed the wrong number of dependents, especially if it affected the amount of any tax breaks you received, like the earned income tax credit (EITC) or child tax credit (CTC).

  • You forgot to include income or reported incorrect income, like if you forgot to include income from a 1099-MISC.

  • You forgot to claim any tax deductions or tax credits.

  • You filed the incorrect income tax form, like if you filed Form 1040NR but should have used a standard Form 1040.

Further reading: 53 tax deductions and credits you can claim in 2021

When should you send an amended tax return?

You have three years from the tax return’s original due date to file an amended return. A return’s due date is generally Tax Day unless you filed a tax extension, which pushes your due date to October 15 (or the next business day if that date falls on a weekend).

If you expect to receive a tax refund from your original return, the IRS suggests that you wait until you receive your original refund before sending the amendment. It’s possible the IRS will either fix mistakes or request further information before sending your refund, preventing you from having to fill out a whole new return.

Related: Will I get a tax refund this year?

If you already got a tax refund but the amended return will result in a lower refund than what you already got, you can file the amended return at any time but make sure you have enough to pay back the difference between what the IRS sent you and what you should actually have gotten. There are multiple payment options, including a direct bank transfer, credit card payment, or debit card payment. You can make payments through the IRS’ payments page.

If your amended return will leave you with a tax bill, send your amended return and pay your bill as soon as you can. The longer you put off payment, the more you will owe. Late fees and interest start accruing the day after your tax-filing deadline, even if you don’t realize you owe a bill until months or years later. Calculating late fees for a tax return isn’t always easy, so consider finding a tax preparer or accountant.

Where to file your amended tax return

You can currently only file Form 1040-X electronically for 2019 and 2020 tax returns. Use an eligible e-filing partner (including some of this year’s top tax filing services or a human tax preparer). For all other years, you can only file an amended return by physically mailing it to the IRS. The proper mailing address depends on where you live, and there are regular changes to the mailing address so check the most recent instructions of Form 1040-X instructions for your correct mailing address.

When mailing your amended return, you may want to use certified mail, which provides a tracking number and will show you when your return has been received.

If you are sending amended returns for multiple years, mail each return in its own envelope. Make sure you include all additional forms or documents that need to accompany your return.

How to file an amended tax return

You can file an amended federal tax return with Form 1040-X, Amended U.S. Individual Income Tax Return. Use the same form whether you originally filed Form 1040, 1040A, 1040EZ, 1040NR, or 1040NR-EZ.

Does filing taxes stress you out? Start with our guide to filing your taxes.

Form 1040-X instructions, part by part

Form 1040-X looks similar to a regular tax return, but you don’t need to complete all sections unless they apply to you and there is space for you to explain what amendments you need to make to your original return. Don’t forget to attach any necessary tax forms, schedules, or other documents when you file.

Personal information

The top of the form is for personal information like your name, Social Security number, and address. Make sure to use the correct filing status. You also need to check the box next to the year of the return that you’re amending.

Form 1040-X Part I

Part I is the longest part of Form 1040-X. It has 30 lines across multiple sections covering your adjusted gross income (AGI), the value of your deductions and credits, your tax liability, any tax payments you made (like estimated tax payments), and any refund you received or should receive. There is also a section for information about your dependents, but you should only fill it out if you need to correct the information about your dependents and exemptions.

There are three columns in most of Part I:

  • Column A is where you write the amounts on your original return (on the tax return that you’re correcting).

  • Column B is for the difference between what you originally reported and the corrected amounts. This shows how much you’re changing the amounts on your original return.

  • Column C is where you write the corrected amount for each value.

Form 1040-X Part II

Part II of Form 1040-X is just for contributions to the Presidential Election Campaign Fund, which goes toward the public financing of primary and general elections. You can only give money if you didn’t contribute on your original return.

Form 1040-X Part III

Form 1040-X’s Part III is a box where you have to describe why you’re filing an amended return and what of the changes you’re making to your original return.


Finish by signing, dating, and writing your occupation at the bottom of the form. If you’re working with a tax preparer, they will also sign and date.

Where’s my amended tax return?

You can check the status of your amended return with the IRS’ Where's My Amended Return? but it can take up to three weeks from the date you mail your return for it to appear in the IRS’ system. Once the IRS has your return, processing can take up to 16 weeks.

To check your amended return status, you need to enter your zip code, date of birth, and either your Social Security number or your individual tax ID number (ITIN).