The Federal Insurance Contributions Act (FICA) tax is a United States federal payroll (or employment) tax imposed on both employees and employers to fund Social Security and Medicare—federal programs that provide benefits for retirees, disabled people, and children of deceased workers. (In the United States, the term payroll tax usually refers to the FICA tax; income tax refers to other federal and state employment taxes.)
The tax also provides funds to the health care system for institutions that provide healthcare for workers that do not have health insurance and cannot afford healthcare treatment. Social Security benefits include old-age, survivors, and disability insurance (OASDI); Medicare provides hospital insurance benefits for the elderly. The amount that one pays in payroll taxes throughout one's working career is associated indirectly with the social security benefits annuity that one receives as a retiree.