The rumor that members of Congress do not pay into Social Security is absolutely false.
Prior to 1984, neither federal civil service workers nor Members of Congress paid taxes to Social Security, nor were they eligible for 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 (P.L. 98-21) required federal employees 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.