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 (PDF) 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

Source: www.irs.gov