1. When to use Form 1040X
You can file Form 1040X to amend a previously filed tax return that used one of these forms:
You will be able to correct any mistakes, including:
- Filing status
- Deductions or credits
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2. Not all mistakes require an amended return
You do not need to file a 1040X if your original return contains math errors or is simply missing forms, such as a W-2. The IRS will usually correct and notify you about math errors and will notify you if it's missing any forms.
3. Amended return timing
If the correction results in you owing money, file as soon as possible so you can minimize any penalties or interest that might be incurred. Although the IRS appreciates when taxpayers file an amended return to correct a mistake, they can still assess a penalty or charge interest for not paying the proper amount when the taxes were originally due.
If the correction results in a tax refund and you haven't received it yet, wait to file the amended return until after you've received it to avoid complications. But keep in mind that there is a time limit for filing an amended return resulting in a refund. You must file it within three years after you filed the original return, or within two years after you paid any tax due from that return—whichever is later.
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4. Preparing an amended return
To complete a Form 1040X, you'll need:
- A copy of the original tax return that's being amended
- Corrected information and calculations
- Any forms needed to support corrections
However, you should not include the original return with the 1040X.
Note: Beginning in 2020 you can file a 1040X electronically but only for the tax year 2019 and later. For earlier tax years an amended returns have to be filed on paper.
5. Stating the reason for the amended return
Form 1040X, Part III, asks you to explain in your own words why you are amending the return. This explanation should describe the specific corrections you're making and can be very brief. Reasons might include:
- You forgot to claim the Child Tax Credit.
- You received another or corrected, W-2 form.
- You forgot to deduct a charitable donation.
6. But now I owe money
If you owe money as a result of the correction, you should include a check or money order with your 1040X submission. You can pay the balance you owe online, using Direct Pay or the Electronic Federal Tax Payment System (EFTPS). If you can't pay right now, file the amended return and apply for an IRS Installment Plan.
7. Mailing instructions for paper-filed amended returns
Each tax return you are amending requires its own Form 1040X mailed in a separate envelope. Mail the completed form to the appropriate address listed in the instructions on Form 1040X.
8. After you mail the 1040X
It takes about 16 weeks for the IRS to process an amended return. You can check its status on the IRS website after three weeks, or by calling the automated toll-free number 866-464-2050.
9. Check the status of your amended return
Use the IRS's new tool Where's My Amended Return to check on the status of your Form 1040X.
10. Amending your state tax return
After submitting Form 1040X, check to see if your state tax form also needs to be amended. If so, obtain the proper form from your state's tax agency and use the information on the federal 1040X to help you fill it out. Be sure to attach a copy of your 1040X to your state amended return.