Tax Form 1040X Instructions

Elizabeth Rosen
by Elizabeth Rosen, Contributor

IRS Tax Form 1040X is the federal Amended U.S. Individual Income Tax Return.

It is designed for taxpayers who need to correct mistakes made on Tax Form 1040, Tax Form 1040A, Tax Form 1040EZ, Tax Form 1040EZ-T, Tax Form 1040NR, or Tax Form 1040NR-EZ. In addition to filling out Tax Form 1040X, you must also fill out a new Form 1040 (even if you are amending a 1040A or 1040EZ), so that the lines can match up with the amended return. While compiling Tax Form 1040X, you must attach the forms/schedules that are being amended (including your 1040 Form or W-2).

You do not need to file IRS Tax Form 1040X if you are only correcting errors in math ― IRS computers automatically check the math and make those corrections for you.

As you prepare to file Tax Form 1040X, make sure you know what you originally reported, what your corrections are, and the reason(s) you are making the changes ― you will need to provide this information on your form. Be clear and concise in your explanation of why you are making the change(s). On the top of the form, write what tax year the 1040X Form is for, because it is a generic form that can apply to any year.

Form 1040X has three columns:

  • Column A: Reports numbers and figures from your original return
  • Column C: Reports the corrected numbers and figures
  • Column B: Reports the difference between Columns A and C

[NOTE: Column C should be equal to the sum of Column A plus Column B.]

In addition to filling out Tax Form 1040X, you must also fill out a new Form 1040 (even if you are amending a 1040A or 1040EZ), so that the lines can match up with the amended return.

While compiling Tax Form 1040X, you must attach the forms/schedules that are being amended (including your 1040 Form or W-2).

Form 1040X can only be filed by paper ― it cannot be done online. You must file separate amended returns for each tax year, and mail each 1040X Form in a separate envelope.

IRS Tax Form 1040X must be filed after the original return has been filed. If you are expecting a tax refund or credit, Form 1040X must be submitted within three years after the original return was filed, or within two years after the tax was paid (whichever is later).

Once your 1040X Form has been received, it normally takes the IRS 8 – 12 weeks to process. If you are expecting an additional tax refund, it will most likely be mailed to you as a paper check, even if you received your initial refund through Direct Deposit.