How to Amend a Tax Return (Form 1040-X): When and How to Fix a Mistake
Found a missing W-2, a forgotten 1099 or a credit you didn't claim? You fix a return you've already filed with Form 1040-X. Here's when you need one, when you don't, and how long it takes.
By the Enrolled Agents and CPAs at A&W Tax Services · Updated
When you should amend
- You left off income, such as a late W-2, a 1099 or a brokerage statement
- You missed a deduction or credit, such as education credits, the EITC or a dependent
- You used the wrong filing status
- You claimed a dependent you weren't entitled to, or missed one you were
- A corrected form (a W-2c or corrected 1099) changes your numbers
When you don't need to amend
Simple math errors are usually corrected by the IRS when it processes your return. If you forgot to attach a form, the IRS will generally write and ask for it. And if you've already received a CP2000 notice about missing income, respond to the notice instead of filing a separate amendment.
Deadlines
To claim a refund, file the 1040-X within three years of the date you filed the original return, or within two years of the date you paid the tax, whichever is later. Returns filed early are treated as filed on the due date. If the amendment means you owe more, file and pay as soon as possible to limit interest and penalties.
How to file
- Use Form 1040-X for the year you're correcting. Recent years can be e-filed
- Show the original figures, the corrected figures and the difference, with a short explanation
- Attach any new or changed forms and schedules
- File a separate 1040-X for each year you're correcting
- If you moved from another state, check whether that state's return needs amending too
How long it takes
Amended returns are processed by hand and commonly take 16 weeks or longer. You can check progress with the IRS tool Where's My Amended Return about three weeks after filing. If the IRS asks questions or adjusts the amendment, it will write to you.