What is Amended Return (Form 1040-X)?
Form 1040-X corrects a return you already filed — to fix income, add a missed deduction or credit, or change your filing status.
How it works
You show the original numbers, the change, and the corrected figures, with a short explanation. You generally have three years from the original filing to amend and still claim a refund. Many amended returns can now be e-filed.
A quick example
What people get wrong
Don't rush to amend for tiny math errors — the IRS fixes those automatically. Amend when income, deductions, credits, or your filing status were actually wrong.