when did it become mandatory to have a social security number
Social Security number Social Security numbers were first issued by the Social Security Administration in November 1935 as part of the New Deal Social Security program. Within three months, 25 million numbers were issued.[4]
History of Social Security in the United States Medicare and Medicaid were added in 1965 by the Social Security Act of 1965, part of President Lyndon B. Johnson's "Great Society" program.