CSRS Retirement Eligiblity
Under the Civil Service Retirement System (CSRS), you must have at least 5 years of creditable civilian service to be eligible for an annuity.
Additionally, you must comply with the "1 out of 2" rule; that is, you must be be subject to CSRS for 1 out of the 2 years of service before separation on which your retirement is based (this requirement does not apply in disability retirement cases).
Voluntary optional, early retirement, discontinued service, disability, and deferred retirement. more
Optional & mandatory retirement for Law Enforcement, Firefighters & Air Traffic Controllers more
If agency undergoes major reorganization, reduction in force (RIF), or transfer of function, OPM may permit early optional retirement. more
Discontinued service retirement because of an involuntary separation (separation against the will and without consent of the employee, other than "for cause" for misconduct or delinquency) more