If for any reason you need to amend a previously filed tax return, you must use Form 1040X, Amended U.S. Individual Income Tax Return, to correct the error or to reflect a change in tax status.
The files are in Adobe Portable Document Format (.pdf), and you will need the free Acrobat Reader to view and print the files.
Downloads:
Form 1040X, Amended U.S. Individual Income Tax Return
Instructions for Form 1040X, Amended U.S. Individual Income Tax Return