1040X

1040X, or Form 1040X, Amended U.S. Individual Income Tax Return, is the IRS form used to correct errors on a previously filed Form 1040, 1040-SR, or 1040-NR, or to claim a refund resulting from those corrections. A 1040X shows the amounts originally reported, the changes being made, and the net tax impact. You must explain the reasons for each change in Part III and attach any schedules or forms that are affected or support the amendment. The form is filed for the tax year being amended, and if more than one year needs correction, you generally file a separate 1040X for each year.

When to file: you generally must file Form 1040X within three years after the date you filed your original return or within two years after you paid the tax, whichever is later. If amending to claim a refund, the same deadline applies.

How to file: most amendments are submitted on Form 1040X, and you should attach copies of any forms or schedules that are changed and any supporting documentation. In many years, the IRS allows electronic filing for amended returns; otherwise, you must mail the form to the address specified in the instructions for your state. If you are filing by mail, use the address listed in the 1040X instructions and include any required supporting documents, such as corrected W-2s or 1099s.

Processing and outcome: amended returns typically take longer to process than original returns. You can check status after the IRS acknowledges receipt. Depending on the changes, you may owe additional tax, or you may receive a refund.