Below are the age and service requirements for the CSRS retirement types of regular federal emloyees.  

(Note:  for law enforcement, firefighter or air traffic controller, click here)

CSRS Retirement Types for Regular Employees

Type of CSRS Retirement	Min. Age	Min. Years Service	Special Requirements
Optional  Voluntary  No age reduction  Immediate annuity	62 60 55	5 20 30	None
Early Optional	Any age* 50*	25 20	Your agency must be undergoing a major reorganization, reduction-in-force (RIF), or transfer of function determined by the Office of Per-sonnel Management (OPM).*
Discontinued Service	Any age* 50*	25 20	Your separation is involuntary and not a removal for misconduct or delinquency.
Disability	Any age	5	Must be disabled for useful and efficient service in  current position and any other vacant position at the same grade or pay level within your commuting area and current agency for which you are qualified**
Deferred	62	5	Must have left retirement contributions in fund.

* Annuity is reduced if under age 55.   ** Application must be prior to retirement,or within one year of separation, except in cases of mental incompetence.

Source:  OPM RI 83-1