ramprasadneupane ji let me make sure I understand your question - you received an extra W2 after you filed your tax return in 2009 (the W-2 was for 2008). So the total income you showed on your 2008 tax return was wrong it should have been more; is that right? If that's the case, you should have filed an amended return in 2009 and avoided penalty(if any) and interest charges. Anyhow, you too will have to file 1040X (amended return) for 2008. You will have to pay the taxes as well as the penalty(if any) and interest charges. You have three years in which you can file an amended tax return.


You should file an amended return if you discover any of the following items were reported incorrectly: filing status, dependents, total income, deductions or credits.
Source: http://www.irs.gov/newsroom/article/0,,id=108657,00.html