Under the "new" federal employees retirement system, wheich went into effect in 1983, federal employees do pay FICA. I know - I are one! We do have available the Thrift Savings Plan which is a glorified 401K, but does give a fairly good return on investment, but it is not mandatory to contribute to it. The "old" employees, those hired before 1983 are retiring and with them goes the old "CSRS" Civil Service Retirement Program.
SLB...we also have the Thrift Savings Plan and it really does have a good rate of return, we are very pleased with the amount of money we have made... ...we just recently upped our contribution from 10% to the now allowable 12%..