In the United States, Social Security is the commonly used term for the federal Old-Age, Survivors, and Disability Insurance (OASDI) program. The original Social Security Act was signed into law by President Franklin Roosevelt in 1935, and the current version of the Act, as amended, encompasses several social welfare and social insurance programs.
Social Security is funded primarily through payroll taxes called Federal Insurance Contributions Act tax (FICA) or Self Employed Contributions Act Tax (SECA). Tax deposits are collected by the Internal Revenue Service (IRS) and are formally entrusted to the Federal Old-Age and Survivors Insurance Trust Fund and the Federal Disability Insurance Trust Fund, the two Social Security Trust Funds. With a few exceptions, all salaried income, up to an amount specifically determined by law (see tax rate table below), is subject to the Social Security payroll tax. All income over said amount is not taxed. In 2017, the maximum amount of taxable earnings was $127,200.
With few exceptions, all legal residents working in the United States now have an individual Social Security number. Indeed, nearly all working (and many non-working) residents since Social Security's 1935 inception have had a Social Security number because it is required to do a wide range of things, e.g., paying taxes and getting a job.
In 2015, Social Security expenditures totaled $750.5 billion for OASDI and $146.6 billion for DI. Income derived from Social Security is currently estimated to have reduced the poverty rate for Americans age 65 or older from about 40% to below 10% The Social Security Administration is headquartered in Woodlawn, Maryland, just west of Baltimore.