Why does exact separation date matter, not just retirement age?

Most retirement calculators, including the one on this site, ask for a whole-number retirement age and approximate your years of service as a whole-year age difference — which assumes you separate exactly on your birthday. If your actual planned date is mid-year or mid-pay-period, that approximation can be off by up to 11 months, which changes your pension amount.

Does a partial month of service count toward my pension?

No. OPM credits service in whole months only (FERS Handbook Chapter 50) — a partial month below a full 30 days is dropped, not rounded up.

Exact Years of Service Calculator

Most calculators ask for your retirement age as a whole number and approximate your years of service from there — which assumes you separate exactly on your birthday. If you're planning to leave mid-year or mid-pay-period, this gives you the precise figure to use instead.

Data current as of 2026 · Sources: OPM FERS Handbook Ch. 50

What this doesn't model: A calendar-date calculation, not an official service history — breaks in service, non-creditable time, or a pending redeposit can all shift your actual SCD. Confirm against your SF-50 for anything consequential.

Why whole-year approximations can be off by up to 11 months

A calculator that asks for "years of service today" and a whole-number "retirement age" typically projects your future service as (retirement age − current age) added to what you have now. That math is exact only if you separate on your birthday. Someone planning to retire in, say, March but who won't turn the relevant age until October is actually about 7 months short of what that approximation assumes — or 5 months ahead of it, depending on which direction the rounding falls. For a mid-career or mid-pay-period exit, that gap is worth knowing.

Where to find your Service Computation Date

Your SCD-Leave date appears in Block 31 of your most recent SF-50 (Notification of Personnel Action). It reflects your actual creditable federal service, adjusted for things like breaks in service, military service, or a redeposit — so it's usually a more reliable starting point than your original hire date.

Use the result everywhere else

The decimal-years figure this calculator produces is meant to be plugged directly into any other tool on this site (or the full report) wherever it asks for "years of service" — a more precise input than the whole-number estimate most people use by default.

Your precise years of service, run through the full pension formula is one input. Your full report combines pension, supplement, survivor election, and FEHB into one decision.

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