All About IRS Form 1040X

Did you make a mistake on your income tax return? Don’t sweat it – it happens. Whether you forgot about a tax deduction or credit or you need to include additional sources of income, you can fix those errors by filing an amended tax return. You’ll do this by completing IRS Form 1040X. A financial advisor can also help you avoid mistakes and optimize your tax strategy for your financial goals. Here’s our guide to understanding and filling out the form.

What Is IRS Form 1040X?

IRS Form 1040X is the Amended U.S. Individual Income Tax Return form. It’s what taxpayers use when they need to make changes to a personal income tax return they’ve already filed. Specifically, you can use it to make corrections to IRS Forms 1040 and 1040NR.

If you need to make adjustments to your tax return, you don’t have to completely start over. Within Form 1040X, you’ll only have to update the numbers and details that need to be changed. Once you file it, Form 1040X supersedes your old tax return.

Estimate your federal income tax return with our free tax return calculator.

Deadlines for Filing Form 1040X

Taxpayers have up to three years to file an amended tax return (or up to two years after paying any taxes they owe if that’s later). If you file your taxes early – like in February or March – you’ll have up to three years after the usual April filing deadline to submit Form 1040X. But if you file for an extension, your deadline will be three years from the date you file your tax return.

How to Fill Out Form 1040X

You’ll need to pull out a copy of your original tax return when you’re ready to fill out your amended return. You can make changes in the margins of your old tax return before completing Form 1040X. It might also be helpful to have access to the instructions for the form. You can find that online. To change some of the information you included on your original tax return, you may need to have additional documents in front of you. For instance, you may need your W-2 form if you’re changing your gross income or you want to know how much federal income tax was withheld from your paychecks.

You might also need to attach other forms to Form 1040X. For example, maybe you originally took the standard deduction but you want to try and reduce your tax liability by itemizing your deductions. Since you’re itemizing, you’ll need to submit a copy of Schedule A along with your amended tax return.

It’s a good idea to take your time while you’re filling out Form 1040X. That way you won’t make any additional mistakes. And don’t forget to double-check that you’ve claimed all the deductions and tax credits that you qualify for.

How to Track Your Amended Return

Once you submit Form 1040X, you should expect a longer wait than with a regular tax return. Amended returns often require manual review by IRS staff, and that process can stretch out for several months. Unlike an e-filed Form 1040, which can be processed quickly, amended returns usually take more time and patience.

The IRS gives taxpayers a way to follow the progress of an amended return through the “Where’s My Amended Return?” tool ¹ . You can access it online or by calling a toll-free number. The system will ask for basic information, such as your Social Security number, date of birth, and ZIP code, to verify your identity before showing your return status.

Your amended return will not appear in the system immediately. It usually takes about three weeks after filing before you can track it. From there, the IRS says full processing often takes up to 16 weeks, though it can take longer if your return involves complex changes, missing documents, or issues that need further review.

If your amended return results in a refund, the IRS will send it to you once the review is complete. If instead you owe additional tax, you should make that payment as quickly as possible to reduce penalties and interest. Keeping an eye on the status of your amended return can help you know what to expect and plan your next steps.

Bottom Line

Not everyone’s tax situation is the same. If you need help completing your amended tax return, you can always reach out to a tax professional. You can also contact the IRS directly. If you need to speak with someone from the IRS in person, you can visit a local Taxpayer Assistance Center, but you’ll need an appointment and many locations will be closed after November 2025. And if you’re expecting a tax refund, the IRS usually reviews amendments to tax returns within eight to 12 weeks. So your refund should arrive at some point after that.

Tax Planning Tips

• A financial advisor with tax expertise may be able to help you optimize your taxes and plan for tax season. Finding a financial advisor doesn’t have to be hard. SmartAsset’s free tool matches you with up to three vetted financial advisors who serve your area, and you can have a free introductory call with your advisor matches to decide which one you feel is right for you. If you’re ready to find an advisor who can help you achieve your financial goals, get started now.
• If you want to get a headstart on next year’s tax return, use SmartAsset’s tax return calculator
  to get an estimate of how much you could owe or receive from the IRS.

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