What should I do if I made a mistake on my federal return that I've already filed?

If you made a mistake on your federal return that you've already filed, you should file an amended return using Form 1040-X, Amended U.S. Individual Income Tax Return. Here are the steps and considerations for filing an amended return:

1. Identify the Mistake: Determine the nature of the mistake. Common reasons for amending a return include not reporting some income, claiming incorrect deductions or credits, or needing to change your filing status.
2. Gather Necessary Documents: You will need:
   • A copy of the original return you filed.
   • Any supporting forms, schedules, and worksheets from the original return.
   • Additional forms, schedules, and worksheets required to show the changes you are making.
3. Complete Form 1040-X:
   • Enter your income, deductions, and credits as originally reported.
   • Enter the changes you are making and the corrected amounts.
   • Calculate the tax on the corrected amount of taxable income and determine the amount you owe or your refund.
4. Attach Supporting Documentation: Include copies of any forms and schedules that are being changed or were not included with the original return.
5. Explain the Changes: Provide a clear explanation of the changes you are making on Form 1040-X.
6. Sign the Amended Return: Ensure that you sign Form 1040-X. If filing a joint return, both spouses must sign. If a representative is signing on your behalf, a power of attorney must be attached.
7. Mail the Amended Return: Send Form 1040-X to the appropriate IRS address. If you are responding to a notice from the IRS, mail it to the address shown on the notice.
8. Timing: File Form 1040-X only after you have filed your original return. Generally, for a credit or refund, you must file Form 1040-X within 3 years after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later.
9. Processing Time: Allow the IRS up to 16 weeks to process the amended return. Due to COVID-19 processing delays, it may take more than 20 weeks.
10. State Returns: If you are changing your federal return, you may also need to amend your state return.
11. Payment: If you owe additional tax, you can enclose a check or money order with your amended return.

By following these steps, you can correct the mistake on your federal return and ensure that your tax records are accurate.

Sources:
Publication 17 (2023)
Instructions for Form 1040-X (01/2023)
Publication 1380