Last verified: October 15, 2026, against the sources linked below. Written by Casey Steward.
The FERS basic annuity uses three inputs: your high-3 average salary, your years of creditable service, and your age at retirement (OPM: Computation).
The basic formula
| Situation at separation | Multiplier |
|---|---|
| Under age 62, or 62+ with less than 20 years of service | 1% of high-3 per year of service |
| Age 62 or older with 20 or more years of service | 1.1% of high-3 per year of service |
OPM adds up all creditable service and drops any fractional part of a month.
Worked examples (hypothetical)
- Retire at your minimum retirement age (MRA) with 30 years, $100,000 high-3: $100,000 × 30 × 1% = $30,000/yr ($2,500/mo).
- Retire at 62 with 20 years, $100,000 high-3: $100,000 × 20 × 1.1% = $22,000/yr.
- Retire at 62 with 19 years 6 months: under 20 years, so 1%: $100,000 × 19.5 × 1% = $19,500/yr.
Minimum retirement age (MRA)
Your MRA depends on your birth year (OPM RI 90-8):
| Born | MRA |
|---|---|
| Before 1948 | 55 |
| 1948 to 1952 | 55 + 2 months per year after 1947 |
| 1953 to 1964 | 56 |
| 1965 to 1969 | 56 + 2 months per year after 1964 |
| 1970 and later | 57 |
Immediate retirement eligibility
- MRA with 30 years
- Age 60 with 20 years
- Age 62 with 5 years
- MRA with 10 years (reduced, see below)
The MRA+10 reduction
If you retire at your MRA with 10 to 29 years, OPM reduces the annuity by 5/12 of 1% for each full month you are under 62 (5% per year). There’s no reduction with 30 years, or with 20 years if your annuity begins at 60. Postponing the annuity start reduces or eliminates the reduction.
Example: MRA 57, 15 years, $80,000 high-3. Unreduced: $80,000 × 15 × 1% = $12,000. Five years under 62 = 25% reduction, so $9,000/yr.
Special provision (LEO, firefighters, air traffic controllers, and others)
1.7% of high-3 for each of the first 20 years, plus 1% for each year beyond 20. Example: 25 years, $100,000 high-3 = $34,000 + $5,000 = $39,000/yr.
What reduces the check
- Survivor benefit: a full (50%) survivor annuity reduces your annuity by 10%; a 25% survivor annuity reduces it by 5% (OPM).
- MRA+10 age reduction (above).
- Taxes and FEHB/FEGLI premiums withheld from the annuity.
COLAs
Most regular FERS retirees don’t receive cost-of-living adjustments until age 62. Special-provision, disability (in most cases), and CSRS-component retirees are exceptions (OPM).
Not covered here
Leaving before retirement? See FERS deferred retirement: quitting at 45 with 20 years.
The FERS annuity supplement, sick leave credit, military buyback, and disability retirement each change the math and will get their own guides.
FAQ
What percent of my salary will my FERS pension be?
Roughly 1% per year of service: 30 years gives about 30% of your high-3, or 33% at 62+ with 1.1%.
Is the FERS pension calculated on gross or base pay?
On high-3 basic pay, excluding overtime and bonuses.
Run your numbers: FERS pension calculator