Part-Time Work &
your annuity.
Part-time federal employees receive full credit toward retirement eligibility — but the annuity calculation is a different story. A proration factor adjusts your benefit to reflect the actual hours worked, and the rules changed significantly on April 7, 1986.
What part-time work
actually changes.
Many federal employees work part-time at some point in their careers. It's important to understand exactly what is and isn't affected — the answer may be more nuanced than you expect.
Part-time employees receive full-time credit for retirement eligibility — those years count the same as full-time years toward reaching the age and service thresholds for retirement. But the annuity computation is different.
Your high-3 average salary is also unaffected by part-time status — it is based on your salary rate, not the hours you worked. The proration only applies to the annuity calculation itself, not to the salary figure used in that calculation.
Part-time service isn't penalized — it's simply adjusted. You receive credit for the hours you actually worked, proportionally.
The proration calculations are complex, and the rules changed on April 7, 1986. OPM's published guidance is vague on this topic — the detailed examples are buried in Chapter 55 of the CSRS/FERS Handbook. If you have any part-time service in your record, always request a formal annuity estimate from your HR office rather than relying on a basic calculator.
Before April 7, 1986
Pre-1986 service is computed using total creditable service through April 6, 1986 — includes unused sick leave as of separation. No proration applied to this period.
1986
CSRS: No proration on pre-April 1986 service
All creditable service through April 6, 1986 counts in full toward the annuity — regardless of whether it was part-time or full-time.
April 7, 1986 onward
Post-1986 service is computed separately and then prorated using the actual hours worked vs. full-time hours possible during that period.
1986
CSRS: Proration applies from April 7, 1986
The post-1986 annuity component is reduced by the proration factor — reflecting actual hours worked as a percentage of possible full-time hours during that period.
CSRS & FERS
proration calculations.
Each system has its own proration formula. CSRS splits the calculation at April 7, 1986. FERS applies a single proration factor across all creditable FERS service, including credited military service.
CSRS Proration
Two-part calculation — split at April 7, 1986
If you have part-time service before and after April 7, 1986, the computation is done in two separate pieces and then combined. The pre-April 7, 1986 component carries no proration. The post-April 6, 1986 component is prorated.
Result expressed as a percentage, rounded to the nearest whole percent. Applied only to the post-1986 annuity component.
FERS Proration
Single factor across all creditable FERS service
FERS uses a single proration factor applied to the entire FERS annuity — including any military service credited under FERS. There is no split calculation based on a date.
Applied to the entire FERS annuity calculation — including any FERS-credited military service periods.
How to work part-time
before and after retirement.
Part-time before retirement — phased transition
Working part-time in the years before retirement is a common transition strategy. The key things to understand:
High-3 not affected: Your part-time schedule does not reduce your high-3 average salary — it is based on your salary rate, not the hours you work. If your salary rate is $80,000 while working 50%, your high-3 reflects $80,000, not $40,000.
Annuity is prorated: The final annuity calculation will apply the proration factor for any part-time period after April 6, 1986 (CSRS) or for the full FERS period. This is not a penalty — it reflects proportional credit for hours actually worked.
Before making this transition, request a formal retirement estimate from your HR/benefits office showing the annuity calculation both with and without the part-time proration. The difference may inform your decision.
Returning to part-time federal work after retirement
Normally, if you are reemployed as a federal employee after retirement, your new federal salary is reduced (offset) by the amount of your annuity — meaning you effectively work for the difference.
Exception — National Defense Authorization Act (Jan 12, 2010): The NDAA created a limited exception allowing CSRS and FERS annuitants to be reemployed without the salary offset on a short-term basis (less than one year, limited hours). This allows the retiree to receive both their full annuity and their new federal salary simultaneously.
This exception does not apply uniformly across all agencies — the Department of Defense has different law and criteria. There are specific justification requirements an agency must meet to retain an annuitant without the pay reduction. Check with the hiring agency's HR office to determine whether the exception applies to a given position.
Contractor opportunities
If you are considering continuing work after federal retirement, contractor roles are another option worth exploring — particularly for those with security clearances. Federal contractor positions are not subject to the reemployed annuitant salary offset rules that apply to direct federal reemployment.
OPM handbook
& references.
The detailed part-time proration examples are in Chapter 55 of the OPM CSRS/FERS Handbook — CSRS examples from page 6, FERS examples from page 21.