Prior to 1984, neither Members of Congress nor any other federal civil service employee paid Social Security taxes. Of course, the were also not eligible to receive Social Security benefits. Members of Congress and other federal employees were instead covered by a separate pension plan called the Civil Service Retirement System (CSRS). The 1983 amendments to the Social Security Act required federal employees first hired after 1983 to participate in Social Security. These amendments also required all Members of Congress to participate in Social Security as of January 1, 1984, regardless of when they first entered Congress. http://usgovinfo.about.com/library/weekly/aa031200 a.htm