This tax calculator instantly estimates your US federal income tax and finds your tax brackets. Tax brackets show percentage of tax that you pay on additional income. The higher is your taxable income, the higher is your federal tax rate. Suppose that you earn an additional amount of $1000 and you are in 28% bracket. That means your would have to pay additional $280 in federal taxes. Income Tax Calculator shows current and past tax brackets and estimates federal tax for years 2000-2008. It includes an option of different filing status and shows an average tax rate, the percentage of tax that you pay relatively to your total income.