Before 1984, civilian employment with the Federal Government was covered under the
            Civil Service Retirement System (CSRS). In 1987, a second retirement system, the Federal
            Employee Retirement System (FERS), became effective and covered new hires under Social
            Security. Federal employees hired between 1984 and 1986 were automatically converted
            to FERS in 1987. Additionally, during that same year, Federal employees covered under
            CSRS could elect to switch to FERS. Employees previously covered under CSRS who switched
            to FERS, or who leave CSRS employment and are later rehired under FERS, have a portion
            of their FERS benefit computed as a CSRS benefit.
         
         Prior to the Social Security Protection Act (SSPA) of 2004, Federal employees met
            the “last day” exemption to Government Pension Offset (GPO) if they were in FERS on
            the last day of service. The SSPA eliminated the “last day” exemption with certain
            exceptions and established a new GPO exemption effective for claims filed April 1,
            2004 or later. The “last day” exemption may still apply if the Federal employee worked
            their last day of Federal service under FERS coverage prior to July 1, 2004, and the
            employer considered that last day of service in determining the CSRS pension amount.
            For additional information about the “last day” exemption, see GN 02608.102. Beginning April 1, 2004, to be exempt from GPO, Federal employees who voluntarily
            switched from CSRS to FERS before January 1, 1988, must work the last 60 months of
            Federal employment covered under Social Security. Federal employees who discontinued
            participation in CSRS or who elected FERS after December 31, 1987, must have 60 months
            of Federal employment covered under Social Security; the 60 months do not have to
            be consecutive.
         
         Federal employees may need fewer than 60 months of covered employment if their last
            day of government service is between July 1, 2004 and March 1, 2009. This transitional
            provision is explained in GN 02608.107B.3.