This Income Tax Calculator instantly estimates your federal income tax and finds your current tax bracket. "Tax bracket" shows percentage tax rate on the top dollars earned. Suppose you have increased you income by 100 in the current year and you federal income tax rate is 28%. This means that the additional income will be taxed at a 28% rate and you will owe additional $28 in federal tax. This calculator allows you quickly estimate your federal tax, average tax and find your tax bracket.