The short answer is: most federal employees hired on or after January 1, 1987are automatically covered by FERS. That sentence sounds simple. It isn’t, because the exceptions and edge cases are exactly where costly mistakes get made.

If you’re not sure which retirement system you’re actually in — and a meaningful number of federal employees are not — this article will help you find out.

The default rule.

Under 5 U.S.C. § 8401 and OPM’s implementing regulations, a federal employee whose appointment begins on or after January 1, 1987 is automatically enrolled in FERS unless they specifically fit into one of the narrow exceptions where the older Civil Service Retirement System (CSRS) still applies. For the vast majority of career federal employees working today, “when I was hired” is the only question that matters.

The system that applies to you is determined by your hiring date, generally on a position-by-position basis, and it gets recorded on your SF 50. If your SF 50 says “Retirement Plan Code 1” or “Retirement Plan Code K”, you are under FERS.

Who is not automatically under FERS.

Three categories of federal employees fall outside the default rule:

  • Employees with prior CSRS coverage who returned to federal service. If you were in CSRS, separated, and came back, the rules that apply to you depend on the length of your break in service and whether you redeposited any CSRS refund. This is one of the most common sources of confusion I see.
  • Employees in positions that fall under a separate retirement system. Law enforcement officers, firefighters, air traffic controllers, and certain members of the military reserves may be covered by FERS-RAE, FERS-FRAE, or a special-category variant with different rules. The basic FERS framework still applies, but the thresholds differ.
  • Non-appropriated fund (NAF) employees and certain intermittent appointees. Some NAF positions are covered by a different retirement system entirely. Most temporary and intermittent employees are not covered by any federal retirement system at all.

How to verify, in two minutes.

The fastest way to confirm which retirement system covers you is to pull your most recent SF 50from eOPF and look at the retirement plan code box. Code 1 is FERS. Code 2 is CSRS. Code 3 is CSRS Offset. Code 6 is FERS-RAE (Revised Annuity Employees, hired in 2013). Code K is FERS-FRAE (Further Revised Annuity Employees, hired in 2022 or later).

If you don’t have access to eOPF, the second-best verification is your most recent SF 3107 Individual Retirement Record or its modern equivalent in the electronic records system. That document shows every period of creditable service and which retirement system was applied to each one.

Why this matters in practice.

The retirement system code on your SF 50 determines your multiplier, your Social Security offset rules, your retirement eligibility thresholds, and your survivor annuity math. It is also essentially locked in by the position you held when you were hired. An employee who transfers to a new agency keeps their original retirement system coverage.

Knowing your code is the single cheapest piece of due diligence in your whole federal career. The cost of getting it wrong — the cost of assuming FERS when you’re actually CSRS Offset, or vice versa — is the cost of an entire retirement miscalculated.