It depends on the type of mistake that was made. Many mathematical errors are caught in the processing of the tax return itself. If you did not attach a required schedule the service will contact you and ask for the missing information.

If you did not report all your income or did not claim a credit, you are entitled to file an amended or corrected return using Form 1040X (PDF), Amended U.S. Individual Income Tax Return. Include copies of any schedules that have been changed or any Form W-2 you did not include. The Form 1040X (PDF) should be submitted after you receive your refund or by the due date of the return, whichever, is earlier. Generally, to claim a refund, the Form 1040X (PDF) must be received within three years after the date you filed your original return or within two years after the date you paid the tax, whichever is later.

References:

• Form 1040X (PDF), Amended U.S. Individual Income Tax Return
• Tax Topic 308, Amended returns

Many mistakes are corrected in processing and a letter of explanation is mailed at the time the refund is issued. If the mistake was not corrected in processing, you need to file an amended or corrected return using Form 1040X (PDF), Amended U.S. Individual Income Tax Return, as soon as possible. Include copies of any schedules that have been changed or any Form W-2 you did not include. If you return the refund check with a letter of explanation, a refund in the correct amount will be issued when the amended return processes.

References:

• Form 1040X (PDF), Amended U.S. Individual Income Tax Return
• Tax Topic 308, Amended returns

Form 1040X (PDF), Amended U.S. Individual Income Tax Return, is designed with three columns. Column A is used to show the figures from the original return. However, if you previously amended that return or it was changed by the IRS, enter the adjusted amounts. Column C is used to show the correct figures. The difference between the figures in Columns A and C is shown in Column B. On the back of the form you need to explain the specific changes being made on the return and the reason for each change. If the changes involve another schedule or form, attach it to Form 1040X (PDF). Be sure to enter the year of the return you are amending at the top of the form as required.

References:

• Form 1040X (PDF), Amended U.S. Individual Income Tax Return and Instructions
• Tax Topic 308, Amended returns

No, an amended return must be filed on a paper Form 1040X (PDF), Amended U.S. Individual Income Tax Return, and mailed to your servicing center for processing. You may submit the form once your original return has processed.

References:

• Form 1040X Instructions and Form 1040X (PDF), Amended U.S. Individual Income Tax Return and Instructions
• Tax Topic 308, Amended returns

Once accepted, you must allow the e-file return to process before making any changes. You cannot correct a mistake on a federal return which was filed electronically. You need to file an amended or corrected return using Form 1040X (PDF), Amended U.S. Individual Income Tax Return, as soon as possible. Include copies of any schedules that have been changed or any Form W-2 you did not include. The Form 1040X (PDF) is a paper form.

References:

• Form 1040X (PDF), Amended U.S. Individual Income Tax Return
• Tax Topic 308, Amended returns

You will need to contact our assistance line at (800) 829-1040 to receive information on the processing of your amended return. Amended/corrected returns are processed as quickly as possible. However, it could take 8 to 12 weeks to process an amended return.

References:

• Form 1040X (PDF), Amended U.S. Individual Income Tax Return
• Tax Topic 308, Amended Returns

You cannot check the status of a refund for an amended return on the automated tax line or by accessing "Where's my Refund". Amended/corrected returns are processed as quickly as possible. However, it may take 8 to 12 weeks or longer to process the return. If 8 weeks have elapsed and you have not received your refund, call (800) 829-1040.

References:

• Form 1040X (PDF), Amended U.S. Individual Income Tax Return
• Tax Topic 308, Amended returns

At this time, the Form 1040X is not accepted electronically. For general information about e-file, refer to Tax Topic 252, Electronic Filing.

References:

• Tax Topic 252, Electronic Filing
• Electronic Filing Service Form 1040X Instructions