How do I file an amended tax return (Form 1040-X) in 2025?

If you discover an error on a previously filed tax return, such as incorrect income, wrong filing status, or missed deductions/credits, you should file an amended return using Form 1040-X.

When to amend: You have 3 years from the date you filed the original return (or 2 years from the date you paid the tax, whichever is later) to file an amended return and claim a refund. Common reasons include receiving a corrected W-2 or 1099 after filing, forgetting to claim a deduction or credit, or needing to change your filing status.

How to file: Form 1040-X can now be e-filed through most tax software. Previously it had to be mailed, but the IRS began accepting e-filed 1040-X forms starting in 2020. You can also still mail it to the IRS address listed in the form instructions. Include any supporting forms or schedules that changed.

Processing time: Amended returns take approximately 16-20 weeks to process. You can track the status at irs.gov/filing/wheres-my-amended-return or by calling 1-866-464-2050. Do not file a duplicate amended return while waiting.

Important notes: Do not amend for math errors (the IRS corrects these automatically) or for missing forms like W-2s (the IRS will contact you). If you owe additional tax, pay as soon as possible to minimize interest and penalties. If you are claiming a refund, the IRS will issue it after processing the amended return. State returns may also need to be amended separately.