How did the IRS already take it? Was it withholding out of your paychecks or on 1099 income? Any withholding taken out will show up on your 1040 line 17 and be subtracted from the total tax calculated on all your income. The withholding is just an estimated amount to cover the actual tax on your income. So you either get a refund if too much was withheld or you will have a tax due if you didn't send in enough during the year.
Do you have self employment income? There is no withholding on that. You usually need to send in extra quarterly estimated payments yourself directly to the IRS to cover the income tax and the self employment tax. You have to enter any estimated payments you made. They will show up on 1040 line 18d.
