If you were a federal employee hired before January 1, 1987, and you never had a break in service that triggered a conversion to FERS, you are almost certainly still under the Civil Service Retirement System— CSRS. The system has been closed to new enrollees for nearly four decades. It is also, in many ways, more generous than FERS, and it is governed by an entirely separate set of rules that most current HR specialists have only ever read about.

Here is the clean definition, and why a CSRS employee needs to plan with the CSRS rules — not the FERS ones their colleagues use.

The plain-English definition.

CSRS is the defined-benefit pension system that covered most federal civilian employees hired before January 1, 1987. It is funded primarily through employee contributions (7%, 7.5%, or 8% of pay, depending on when you were first hired) and pays a monthly annuity calculated under a separate, more generous formula than FERS.

Crucially, CSRS employees do not pay Social Security taxes on their federal salary, and they are not eligible for Social Security benefits based on that federal service. (They may be eligible based on other employment.) This is the single most important difference between CSRS and FERS, and it changes nearly every other retirement decision in the picture.

The CSRS annuity formula.

CSRS uses a tiered formula based on years of service and the employee’s high-3 average salary:

  • 1.5% per year for the first 5 years of service.
  • 1.75% per year for the next 5 years (years 6 through 10).
  • 2.0% per year for all years beyond 10.

That produces a substantially larger annuity than the FERS 1.0% (or 1.1%) multiplier. A 30-year CSRS employee with a $120,000 high-3 average salary would receive an annual annuity of roughly $69,000— close to double the FERS equivalent under the standard multiplier. The system was, in real terms, one of the most generous defined-benefit pensions ever offered by an American employer.

Who still has CSRS today.

The system is closed, but not empty. CSRS still covers:

  • Federal employees hired before January 1, 1987 with continuous service and no break long enough to trigger FERS coverage.
  • CSRS Offset employees, who had some CSRS-covered service and some FERS-covered service, and pay into both systems.
  • A small number of employees in special category positions that retained CSRS-style coverage by statute.

As of 2026, the population of active CSRS employees is small and aging. Most are within 10–15 years of retirement. That makes the next decade the most consequential window in CSRS history — because the institutional knowledge of how the system actually works is shrinking fast.

Why CSRS planning is different from FERS planning.

Three places where the systems diverge in ways that change the decisions:

  • Social Security.CSRS employees didn’t pay into Social Security on their federal salary, which changes the optimal claiming decision. For a CSRS employee, the “wait until 70” Social Security rule often applies to a much smaller benefit, and the FERS supplement doesn’t apply at all.
  • The TSP match. CSRS employees are not eligible for the FERS agency automatic 1% contribution or the matching contributions. They can still contribute to the TSP, but they do so without the employer match that FERS employees receive. The trade-off is the larger pension.
  • Survivor benefits. CSRS survivor annuity rules differ from FERS in cost and structure, and the consequences of getting the election wrong are different.

The point is not that CSRS is better or worse than FERS. The point is that it is a different system with different rules, and the people most likely to be advising you on it — younger HR specialists, generalist financial advisors, internet forums — often have FERS in their head when they should have CSRS.