Taxes Solving Tax Issues What Is IRS Form 1040-X? By William Perez Updated on January 9, 2023 Reviewed by Michelle P Scott Fact checked by Yasmin Ghahremani In This Article View All In This Article How Form 1040-X Works Where To Get Form 1040-X How to Fill Out Form 1040-X Can Form 1040-X Be E-Filed? Where To Mail Form 1040-X Requirements for Filing Form 1040-X After You File Form 1040-X Frequently Asked Questions (FAQs) Photo: Mikael Vaisanen / Getty Images Definition Form 1040-X is an amended tax return for individuals. It corrects, deletes, or adds information to a Form 1040 return that's already been filed with the IRS. You might find it necessary to file Form 1040-X if a new W-2 or 1099 arrives for income that you'd forgotten about, or if your ex tells you that they also claimed your child as a dependent. Key Takeaways Form 1040-X is an amended tax return that allows you to correct a previous return on which you made mistakes.You can correct virtually any inaccurate information on Form 1040-X, from your claimed dependents to income you reported, to deductions and credits you previously claimed.The form provides a dedicated section where you can explain what you’re changing and why.You have three years to file Form 1040-X if the changes you're making will result in a refund or an increased refund. How Form 1040-X Works Form 1040-X effectively replaces a Form 1040 that contained errors. It allows you to set things right with the IRS, but it doesn't just include the changed information. The correct information from your previous return must be transferred from your Form 1040 to Form 1040-X as well. File amended tax return Form 1040-X if the information you're correcting will alter the tax calculations on your original return. For example, if you claimed the wrong filing status, or need to change information about your income, deductions or credits you should file a Form 1040-X. You can also use the form to make certain elections after the Tax Day deadline or claim a carryback from a loss or unused credit. Note You don't usually need to file an amended return to correct math errors. The IRS computers check your math and will generally correct any errors in calculation. Where To Get Form 1040-X Form 1040-X is available on the IRS website. You can print out a copy and fill it out by hand, or you can enter your information into the interactive form and then save and print out a completed version. Most reputable tax software also prepares amended returns and allows you to file electronically. How To Fill Out and Read Form 1040-X Make sure you have both your original tax return and Form 1040-X in front of you when you begin making changes because Form 1040-X basically summarizes the information you're changing. Each section of the form is clearly marked as to what information you should enter and where. Indicate the tax year of the return you're amending at the top of the first page of Form 1040-X. Make changes to your reported income and to tax deductions you claimed on page 1, lines 1 through 5, "Income and Deductions." You can amend your standard deduction or itemized deductions here. You can claim additional tax credits that you missed when you filed your original return on page 1 as well, or remove tax credits mistakenly taken or recalculate the amount of the credits. This information is entered under "Payments," lines 12 through 17, because credits effectively act as payment of any tax obligation you owe. Enter corrected information about your dependents in Part I on page 2, lines 24 through 30. This is the appropriate section if you initially entered a wrong Social Security number for one of them, if you want to drop one or more dependents, or if you want to add one or more. Calculations for your refund or the amount you owe the IRS go on lines 18 through 23 on the first page of Form 1040-X. You'll have to reimburse the IRS if you received a larger refund from your original tax return than you should have. Make a payment (electronically or by check) for the difference to avoid interest and penalties. Do not staple or otherwise attach the check to your Form 1040-X. The most important part of Form 1040-X is probably Part III, on the second page. This is where you can explain the changes you're making to your previous tax return. Your Part III explanation might read like this if you forgot to include wages from a W-2 on your original return: "I am reporting additional W-2 wages and withholding that weren't included on my previous tax return. This resulted in changes to my adjusted gross income, taxable income, total tax, and my refund." Try to be as concise as possible. Point the IRS to the specific changes you're making, and tell them where they can find proof of those revisions in your supporting documentation. Can Form 1040-X Be E-Filed? Yes, the IRS has accepted e-filed Forms 1040-X since 2020. Where To Mail Form 1040-X You can mail your amended return to the same IRS Service Center that processed your original tax return if you prefer to send in a paper copy. The IRS also provides a comprehensive list of mailing addresses on its website for various circumstances that require filing an amended return and depending on your state. Be sure to include any and all schedules that you've changed, and any new Forms W-2 or 1099 that represent changes from the information you filed with your original return. Attach the W-2s or 1099s to the front of Form 1040-X if you're mailing in a paper copy. Requirements for Filing Form 1040-X You have three years to make any corrections that will result in a tax refund or an additional refund. That's the IRS statute of limitations on issuing refunds. This three-year period begins on the return's due date, which is usually April 15, if you filed your original return on or before that date. But it runs from the date you filed if you filed later than April 15, such as because you requested an extension. You can only receive refunds for overpaid taxes that were paid during the previous two years if you're beyond this three-year period. You can't collect any refundable tax credits you might have missed claiming when you filed your original return if you wait too long. Taxpayers who want to report additional income or correct overstated deductions can file an amended return at any time. The IRS also has three years to audit your tax return, and it might have still more time if there's been substantial under-reporting of income. After You File Form 1040-X The IRS Service Center will make sure your explanations are sufficient and that you've documented the changes you made to your tax return. You'll receive a letter asking for any specific information needed if the IRS requires more explanation or additional documentation. The IRS scrutinizes amended tax returns a little more carefully during processing, so take extra care to make sure your Form 1040-X is as complete and accurate as possible. The IRS is likely to process your amended return without fuss if you clearly explain why you're correcting your tax return and if you back it up with proper documentation. The IRS agent can look up corroborating information on the IRS computer, but it will be easier and more efficient if they can see the documentation right there with your amended tax return. There's no conclusive evidence that an amended tax return will trigger an audit. The IRS uses the same screening process for Forms 1040-X that it uses for regular returns. Frequently Asked Questions (FAQs) What's the difference between a 1040 and 1040-X? Form 1040 is the standard individual tax form. 1040-X allows you to make changes to the 1040 (as well as 1040-SR and, for tax years 2021 and later, 1040-NR) after you have filed it. The 1040-X asks similar questions and requires you to input all of the information you submitted on your 1040, but it has columns that ask you for the correct information and any net change in numbers. What forms do I mail with 1040-X? Include copies of any forms or schedules you are changing or that you didn't include in your original return. For example, if you're changing deductions that you claimed, you'll need a copy of Schedule A. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit Sources The Balance uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. IRS. "Amended Returns & Form 1040X." Internal Revenue Service. "Now Available: IRS Form 1040-X Electronic Filing." IRS. "Topic No. 308 Amended Returns." IRS. "IRS Audits."