It's a good idea to have all your tax documents together before preparing your 2012 tax return. You will need your W-2, Wage and Tax Statement, which employers should send by the end of January. Give it two weeks to arrive by mail.
If you have not received your W-2, follow these three steps:
If you need more time to file, you can get a six-month extension of time. File Form 4868, Application for Automatic Extension of Time to File US Individual Income Tax Return. If you are requesting an extension, you must file this form on or before April 15, 2013.
If you receive the missing W-2 after filing your tax return and the information on the W-2 is different from what you reported using Form 4852, then you must correct your tax return. File Form 1040X, Amended U.S. Individual Income Tax Return to amend your tax return.
Forms and instructions are available at IRS.gov or by calling 800-TAX-FORM (800-829-3676).
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