I filed my federal income taxes already but forgot to add a w2?

I have already filed my taxes this year but forgot to add one of my w2's. I worked at another job breifly and forgot about the w2. Can I just hold on to the w2 and add it to my taxes next year and just pay a penalty or something? Also, how much would the penalty be if I do that?

Public Comments

1. Amend your return ASAP. 2006 income MUST go on a 2006 return.
2. No, you must use it for this year's return. Use Form 1040X, Amended U.S. Individual Income Tax Return, to correct a previously filed Form 1040, Form 1040A, or Form 1040EZ. If you are filing to claim an additional refund, wait until you have received your original refund (you may cash that check). To avoid penalty and interest, if you owe additional tax for a current year amended return, file Form 1040X and pay the tax by April 15 of the current year.