A system that became effective in 1987 and replaced the Civil Service Retirement System (CSRS) as the primary retirement plan for U.S. federal civilian employees. Retirement benefits under FERS are accumulated in three ways: a) through Social Security benefits, b) through a basic benefit plan for which the employee is charged a nominal amount and c) through a Thrift Savings Plan (TSP), which comprises automatic government contributions, voluntary employee contributions and matching government contributions.

Retirement benefits under FERS are structured as annuities. Eligibility and payment amounts are based on age, years of service and contributions to the plan. Although less generous than CSRS was, FERS is more generous than many corporate plans.

Federal employees hired after 1983 are automatically covered by FERS, rather than CSRS.