What Is Form 1040X?

If you discover an error on your income tax form after you've submitted it, you can use IRS form 1040x to help correct the error.

What Form 1040X Does

Form 1040X is simply a short form you need to submit along with your amended tax return. Instead of being a new tax return, form 1040X lists only the changes from your old tax return to your corrected one.

For example, suppose you realize you forgot to report some income from a home business. In that case, you would complete a second tax return with the correct income. Then, on form 1040x, you would report each of the changes you made from your old tax return to your new one--the new income and any other additional tax you need to pay on it. This helps the IRS identify exactly what items were changed on your corrected form.

Also, you must report the reason for your change on form 1040x. In our example, you would simply explain that you neglected to report income from a home business.

Using Form 1040x

You can submit 1040x, along with your corrected tax return, up to three years after you submit the incorrect return. You can get a copy of form 1040x directly from the IRS website.