We all make mistakes. And occasionally, those mistakes happen to involve a federal income tax return. For just those occasions, the IRS has created the federal form 1040-X (downloads as a pdf).

The form 1040-X is surprisingly short: a mere two pages long. That’s because it’s not meant to be a new return, just an improved one. In other words, the IRS wants you to use the form 1040-X just to correct your errors. Do not file another “original” return since that will just confuse the IRS and will delay processing of your return (and your refund if you’re entitled to one).

The front page of the form 1040-X is a summary sheet, which asks you to list your prior amounts as reported, the correct amounts and the difference between the two. You’ll next calculate any net tax difference.

The second page allows you to make adjustments to exemptions (only if necessary), elect to contribute to the Presidential Election Fund (though oddly enough, not to revoke a prior choice to contribute) and finally, explain the reason for the changes on your return.

Simple, right?

There are a few things to keep in mind:

  • File a separate form 1040-X for each affected tax year.
  • With respect to timing, you should file form 1040X within 3 years after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later. If you filed earlier than the due date, use the due date (April 15). If you filed on extension, use the actual date of filing.
  • Check the instructions carefully to determine where to file your form 1040-X. The place of filing depends on the type of original return (EZs and NRs, for example, have a different address) and where you live.
  • This isn’t the form to use if you’re simply requesting a refund of penalties and interest or an addition to tax that you have already paid. Instead, use a form 843, Claim for Refund and Request for Abatement (downloads as pdf).
  • This also isn’t the form to file for an injured spouse claim. That’s a federal form 8379, Injured Spouse Allocation (downloads as pdf).
  • Be patient. A form 1040-X usually takes 8 to 12 weeks to process.

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Kelly Erb is a tax attorney and tax writer.


  1. Joe, I think it would depend on why… I recently filed a slew of them for a taxpayer (six years or so).

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