The Federal Insurance Contributions Act (FICA) is a federal law requiring employers to withhold three separate taxes from your wages: a 6.2% Social Security tax, a 1.45% Medicare tax, and (as of 2013) a 0.9% Medicare surtax when your Adjusted Gross Income (AGI) is over $200,000. Because of the Medicare surtax, you may see FICA amounts even after you are no longer employed.