The state of the economy during the Great Depression led to passage of the Social Security Act in 1935. This law provided payments known as “unemployment compensation” to workers who lost their jobs. Other sections of the Act gave public aid to the aged, the needy, the handicapped, and to certain minors. These programs were financed by a 2 percent tax, one half of which was subtracted directly from an employee’s paycheck and one half collected from employers on the employee’s behalf. The tax was levied on the first $3,000 of the employee’s salary or wage.

Beginning in 1956, Social Security began an almost steady evolution as more and more benefits were added, beginning with the addition of Disability Insurance benefits. In 1958, benefits were extended to dependents of disabled workers. In 1967, disability benefits were extended to widows and widowers. The 1972 amendments provided for automatic cost-of-living benefits.

In 1965, Congress enacted the Medicare program, providing for the medical needs of persons aged 65 or older, regardless of income. The 1965 Social Security Amendments also created the Medicaid programs, which provides medical assistance for persons with low incomes and resources.

Of course, the expansions of Social Security and the creation of Medicare and Medicaid required additional tax revenues, and thus the basic payroll tax was repeatedly increased over the years. Between 1949 and 1962 the payroll tax rate climbed steadily from its initial rate of 2 percent to 6 percent. The expansions in 1965 led to further rate increases, with the combined payroll tax rate climbing to 12.3 percent in 1980. Thus, in 31 years the maximum Social Security tax burden rose from a mere $60 in 1949 to $3,175 in 1980.

Despite the increased payroll tax burden, the benefit expansions Congress enacted in previous years led the Social Security program to an acute funding crises in the early 1980s. Eventually, Congress legislated some minor programmatic changes in Social Security benefits, along with an increase in the payroll tax rate to 15.3 percent by 1990. Between 1980 and 1990, the maximum Social Security payroll tax burden more than doubled to $7,849.

source: US Department of the Treasury