Social Security was enacted in 1935 to provide some relief to America's destitute older citizens during the economic cataclysm known as the Great Depression. A direct descendant of that more limited effort, today's Social Security retirement program is in fact a group of related programs, each with its own eligibility and payment rules: retirement, disability, survivors and dependents benefits.

The best known of these programs is retirement, known formally as Old-Age and Survivors Insurance (OASI). Under this program, Social Security provides income to retirees, as well as benefits to a worker's surviving spouse and to a retired worker's children under age 18. As of December 2011, the program was issuing benefits to some 38 million retired workers and their dependents, as well as to more than 6 million survivors of deceased workers.

Social Security retirement benefits are financed primarily through dedicated payroll taxes paid by workers and their employers. The 15.3 percent payroll tax, known as Federal Income Contribution Act taxes (FICA), has two components: Social Security (12.4 percent) and Medicare (2.9 percent). Employees and employers split them both equally. For the Social Security portion, employers pay 6.2 percent of an employee's income, and the employee kicks in the same. Self-employed individuals pay the entire 12.4 percent Social Security payroll tax. However, they may deduct half in figuring their adjusted gross income.

For most retired workers and their dependents, however, Social Security retirement benefits alone are not enough for them to maintain the standard of living they had before retirement. Although Social Security retirement benefits are protected against inflation by annual Cost of Living Adjustments, the estimated average retirement benefit for retirees is only about $1,360 a month, and the survivors of workers receive an average of only $1,285 a month (in 2016). For 2017, the maximum monthly Social Security retirement benefit for a worker retiring at the full retirement age of 66 years is $2,687.

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