Form 1040x amended tax return

If you find errors or you left out information on your original return, file Form 1040X — this is the amended federal return. By filing an amended return, you might:

  • Receive an additional refund
  • Owe additional taxes as a result of the correction

If you’re due a refund, the IRS will send it to you after it accepts your amended return. If you owe tax, send the amount owed to the IRS along with Form 1040X. If you owe interest or a penalty, the IRS will bill you.

When you file a Form 1040X, attach these items if you’re required to show them to back up the changes on your amended return:

  • Forms
  • Schedules
  • Statements

When you amend a return for a specific reason, it’s a good idea to review your entire original return. Look for deductions, credits, and exemptions that you might have missed the first time around.

Due date for filing Form 1040X

You usually must file an amended return by the later of these dates:

  • Within three years from the date you filed your original return
  • Within two years from the date you paid the tax

If you filed your return on or before the filing deadline, April 15 is considered the filing date. If you received an extension, the filing date is one of these:

  • Actual date you filed your return within the extension period
  • April 15, if you filed your return after the extension period expired

If you’re filing an amended return due to a bad debt or a worthless security, you have more time to file. In this case you have seven years after your original return’s due date to file the amended return.

You can also file an amended return for a year when you carried a net operating loss (NOL). You must file the amended return within three years of the due date of the return for the year when the NOL arose.

The IRS usually has three years to assess additional taxes. However, longer periods apply for significant underreporting of income or fraud.

Completing Form 1040X

To file an amended return, download and file Form 1040X from You must mail this form. You can’t e-file it.

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