10/02/2026
Don't panic.
A mistake doesn't necessarily mean you're in serious trouble.
Depending on the circumstances, you may need to correct the return.
For many individual federal returns, this can involve Form 1040-X, Amended U.S. Individual Income Tax Return.
Example
Suppose someone files their return.
Two weeks later they receive a corrected tax document and discover the information differs from what they reported.
The taxpayer may need to amend the return.
The IRS specifically notes that if a taxpayer files using an estimate because a document was missing and later receives a corrected document that differs from the estimate, they may need to file Form 1040-X.