Amended Tax Return: How to File Form 1040-X

An amended tax return corrects mistakes on a federal tax return. Here's how to file an amended tax return with the IRS, when to amend a tax return and other rules you need to know.

What is an amended tax return?

IRS Form 1040-X, also known as an amended tax return, is a form that taxpayers can file with the IRS to correct mistakes made on a federal tax return. The form is typically used to fix errors concerning tax liability, filing status, income or deductions/credits claimed^[0]

Taxpayers can also submit an amended tax return to claim a refund due for credits or deductions they were eligible for but did not claim on their original return.

When to amend a tax return

If you catch a major error before the IRS does, or you receive new tax documents after you’ve already filed, you may need to amend your original return by filing Form 1040-X.

Here are quick guidelines for when to file an amended return:

• You used the wrong tax filing status.

• You misreported your dependents.

• You forgot to include certain taxable income.

• You incorrectly claimed (or forgot to claim) a tax deduction or credit.

Some mistakes, such as a math error, may not warrant filing an amended return, according to the IRS^[0]

» MORE: See a list of IRS phone numbers you can call for help

How to amend a tax return

To amend your return, you'll need to fill out Form 1040-X. Many online tax software programs support filing an amended return electronically and can walk you through the steps of filling out the form.

Before you begin, give your original return a thorough review to make sure you've accounted for all the things you need to correct. Then, gather any tax documents you may need to reference while filling out the amended return. If you're correcting income, for example, this could mean grabbing that Form 1099 you overlooked or a revised W-2 you received after submitting your original return.

If you choose to file your amended return by paper, you can download Form 1040-X directly from the IRS website. Make sure to include any forms or schedules that were included in your original filing, as well as any new forms or schedules necessary to process your return^[0]

Note: If you need to file an amended return for a Form 1040, 1040-SR, 1040-NR or 1040-SS/PR originally filed more than three years ago, the amended return must be filed on paper and sent to the IRS by mail. The same goes for any return that was originally filed by paper during the current year^[0]

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Can I file an amended tax return myself?

People with simple tax situations and small changes might be able to file an amended tax return on their own. Many major tax software packages include features that will file an amended tax return. If you're amending your federal tax return, note that could mean having to amend your state tax return, too.

You can file up to three amended tax returns electronically, but note that if you’re fixing more than one year of returns, you’ll need to fill out a separate Form 1040-X for each.

Will my tax preparer amend my return for me?

Many tax preparers are happy to file amended returns but don’t assume they will amend your tax return for free. Also don't assume that they'll pay any additional taxes, interest, or penalties you're on the hook for because of a mistake. For example, if you forgot to give the preparer information or gave incorrect information, you’ll likely have to pay for the extra work. If the error is the preparer’s fault, it's still not a sure bet that they'll pay for the amended return. That may depend on the wording in your client agreement.

» MORE: How to get rid of your back taxes

Will the IRS know if I don't amend my return?

Generally, the IRS audits only tax returns from the previous three tax years, though there are major exceptions^[0]

The IRS charges interest and penalties on outstanding tax liabilities going all the way back to the original due date of the tax payment. So the longer you wait to fix a mistake, the more expensive that mistake can get.