The most authoritative source for the federal income tax rate tables is on the Internal Revenue Service (IRS) website, which also includes information on computing taxes and filing tax returns. As of March 2015, the Bankrate website also offers simplified tax bracket tables for 2014 and 2015.
A person's federal income tax rate depends on marital status, annual income and filing status, such as separately or jointly. The IRS tax tables include columns for each of these items, and a user finds the line with the income range, marital status and filing status to see an example amount of tax due.
Tax bracket tables like those offered on the Bankrate website, however, tell the percentage per dollar of a person's income that must go to federal taxes. Therefore, the person has to calculate the amount rather than see it directly like on the IRS website.