If your filed1040 has all correct amounts, you don't have to attach any forms.
Get Form 1040-X from IRS website and mail it in with your W-2C fed copy attached.
Note: when you are not changing any dollar amounts on your amended tax return, you can leave all the lines 1-23 EMPTY.
Part III explanation: "enclosing corrected W-2 with correct SSN".
Mail to the address specified in the latest Instructions for Form 1040-X.
@marina-matveeva-
