A method that became effective in 1987 and replaced the Civil Service Retirement System (CSRS) as the principal retirement plan for U.S. national civilian workers. Retirement benefits under FERS are collected in three ways: a) through Social Security benefits, b) through a simple benefit plan that the worker is charged a token sum and c) through a Thrift Savings Plan (TSP), which consists of automatic authorities contributions, voluntary worker contributions and matching government contributions.