Form 1040X

DEFINITION of 'Form 1040X'

A form used by taxpayers who have to amend their tax returns for any reason. Form 1040X is an itemized, line-by-line description of all necessary adjustments, so that the taxpayer can clearly record the exact type and amount of each amendment, and give a brief description of what is being amended and why.

BREAKING DOWN 'Form 1040X'

Form 1040X can be downloaded off the Internal Revenue (IRS) website. In most cases, taxpayers who use this form need to also amend their state tax returns. Taxpayers must fill out this form regardless of whether they initially used Form 1040, Form 1040A or Form 1040EZ.

To learn more about this IRS tax form, read When would I need to fill out an IRS Form 1040X when filing my taxes?