Retirement benefits formula for part-time service


Q: I am under the Federal Employees Retirement System and have 25 1/2 years of federal service. Early in my career, I had a few years of part-time employment. What is the formula to figure how this impacts my annuity? A FERS Benefit Estimate Report from the Office of Personnel Managment listed a FERS part-time proration factor of 92 percent at age 50 with 23 1/2 years of service and 94 percent at age 56 1/2 with 30 years of service. I am assuming this means my annuity will be reduced by 6 percent at 30 years of service. If I work beyond 30 years of service, would the that reduction be eliminated? Also, what is the definition of “part-time employment”?

A: Because you had a period or periods of part-time service, your annuity will be prorated regardless of how long you work. You’ll find the formula you’re looking for on the OPM web site here (scroll down to Subchapter 55B, Part 55B2, “Computing FERS Annuities that Include Part-time Service”).


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Reg Jones was head of retirement and insurance policy at the Office of Personnel Management. Email your retirement-related questions to

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