How it works
Form 1040-X amends a return already filed. You generally have three years from the original filing date, or two years from payment, to claim a refund; amending to report additional income can be done at any time. The form shows original amounts, changes, and corrected amounts, with an explanation. Amended returns can be e-filed for recent years and take months to process.
Why it matters
Amending is often the right first step to fix unreported crypto or a mistaken position when the omission was non-willful and domestic. Amending to report foreign accounts or large omitted income without a formal program is a quiet disclosure, which carries risk. Amending does not restart the assessment statute, though the IRS gets at least 60 days to review.
Example
A taxpayer discovers she omitted 15,000 dollars of coin-to-coin trading gains from her 2024 return. She files a 1040-X reporting the gains and pays the tax and interest before the IRS sends a CP2000.
Related: quiet disclosure. Watch: Before You Amend Your Taxes in the media library.
