If you’ve spent any of your federal career working part-time, your FERS part-time service may affect your pension in a way that’s easy to miss. Your high-3 salary can still be based on the full-time rate of basic pay, but your eventual annuity can be reduced through a separate proration calculation.
The High-3 Isn’t the Whole Story
For FERS employees with part-time service, OPM uses the deemed full-time rate of basic pay when calculating the high-3 for the basic annuity. In other words, a period when you worked half-time doesn’t simply turn your high-3 salary into half of the full-time salary. The adjustment comes later.
OPM calculates a FERS proration factor based on your actual hours worked compared with the hours you could have worked as a full-time employee during your creditable FERS service. That factor is then used in calculating the annuity.
Here’s How the Math Works
Consider someone with 25 years of FERS service:
- 20 years full-time
- 5 years part-time
- High-3 average salary: $95,000
For a simplified illustration using 2,087 hours per full-time year:
If you had worked full-time the entire 25 years:
25 × 2,087 = 52,175 hours
Actual hours worked at 5 years half-time:
20 × 2,087 = 41,740
5 × 2,087 / 2 = 5,217.50
Total = 46,957.50 hours
What percentage of the 52,175 possible full-time hours did you work:
46,957.50 ÷ 52,175 = 90%
To put it simply, those 5 years of part-time work during your career resulted in you working 90% of the hours that a full-time employee would have clocked over that same 25-year period. Therefore, you only receive 90% of the full pension.
Using the standard 1% FERS multiplier:
25 × 1% × $95,000 = $23,750
After applying the 10% reduction:
$23,750 – 10% = $21,375
That’s a difference of $2,375 per year, or about $198 per month, before considering other applicable reductions or benefits.
OPM’s actual calculation uses the employee’s specific periods of creditable service and the applicable full-time hours for those periods, so this example is intended to illustrate the concept rather than reproduce an individual retirement calculation.
Part-Time Service Can Still Count Toward Retirement Eligibility
Here’s what makes this confusing: FERS part-time service can still count as service toward retirement eligibility. OPM says each year of part-time service counts as a full year toward the length-of-service requirement, even though the annuity calculation is prorated for part-time service after April 6, 1986.
So an employee could reach a retirement eligibility milestone with the expected number of years while still receiving a smaller annuity because of part-time service.
What About Phased Retirement?
Phased retirement has additional rules. Employees participating in phased retirement work part-time while receiving a partial annuity, and their eventual full-retirement calculation accounts for the additional service they perform.
That’s one reason employees shouldn’t assume that a simple part-time formula applies to every reduced-work arrangement.
Did You Work Part-Time?
If you’ve worked part-time during your federal career, your high-3 might not tell the whole story.
Before you retire, ask your agency’s benefits office for an estimate that reflects your actual service history, including FERS part-time service. OPM specifically recommends that employees considering part-time work obtain an estimate of their retirement benefits.
Your FERS pension is only one part of your retirement income. A Federal Retirement Consultant (FRC®) can help you understand how your pension, Social Security, and TSP fit together as you plan for retirement.
