How Your FERS Pension Is Calculated

Updated June 2026 · Educational only — not financial, tax, or legal advice

Your FERS pension — officially the basic annuity — is the guaranteed monthly check you receive for life in retirement. The good news: the core formula is simple arithmetic. This guide walks through every piece of it, for both Regular FERS and the Special Provisions (law enforcement, firefighter, air traffic controller), with worked examples. When you're ready to see your own number, the free FERS calculator runs all of this for you.

The formula in one line

For most federal employees, the annual FERS basic annuity is:

Three inputs, one multiplication. Everything else in this guide is about getting each of those three numbers right — and the handful of situations where the 1% becomes something else.

The multiplier: 1%, 1.1%, or 1.7%

The percentage applied to your high-3 depends on your situation:

That 1.0% → 1.1% jump is a 10% increase on your entire pension, for life — and it's the reason the age-62 mark gets so much attention. We break down exactly when it's worth it in the 1.1% multiplier guide. (Note: unused sick leave does not count toward the 20 years needed to trigger the 1.1% rate.)

Special Provisions: the enhanced computation

If you retire under the special provisions for law enforcement officers, firefighters, or air traffic controllers, your first 20 years are computed at the richer 1.7% rate, and any service beyond 20 years at 1.0%:

This is one of the most valuable features of special-provision coverage — and most generic calculators get it wrong or ignore it. Ours treats it as first-class.

Input #1: Your high-3 average salary

Your high-3 is the average of your highest 36 consecutive months of basic pay — almost always your final three years. "Basic pay" includes your locality pay but excludes overtime, bonuses, and most premiums. Because it's an average of your highest-earning years, working a few extra months near the top of your career can nudge it upward. We cover exactly what counts in the high-3 guide.

Input #2: Your years of creditable service

This is the total time that counts toward your annuity — generally your federal civilian service, plus military service if you've made the required deposit, plus a credit for unused sick leave. Two things to know:

• Unused sick leave is added to your service for the computation (2,087 hours = one year), but never counts toward eligibility. See the sick leave credit guide — including the rounding trap that can quietly cost you days of credit.
• Service is counted in years and months. Partial months are generally dropped, which is why your exact retirement date matters — see the best-date guide.

Worked example — Regular FERS

A regular FERS employee retires at 60 with a $100,000 high-3 and 30 years of service (no enhanced rate, because they're under 62):

The same employee working to 62 with 32 years would get the 1.1% rate: 1.1% × $100,000 × 32 = $35,200/year — a meaningful jump from both the higher multiplier and two more years of service (and likely a higher high-3).

Worked example — Special Provisions

A law enforcement officer retires at 50 with a $95,000 high-3 and 25 years of special service:

What this number does not include

The basic annuity above is a gross, self-only figure. Your actual deposit will be lower after any of these apply:

• Survivor benefit election — choosing a survivor annuity reduces your monthly amount (typically by about 10% for the full election).
• Federal taxes — your annuity is largely taxable income.
• FEHB and FEGLI premiums — if you carry health and life insurance into retirement.

And before age 62, eligible retirees also receive the FERS Annuity Supplement on top of the basic annuity — a separate payment that bridges you to Social Security.