How to calculate your FERS pension

OPM computes the FERS basic annuity with a single formula: High-3 average salary times years of creditable service times a pension multiplier. Each of the three inputs moves independently, which is why two employees with similar salary histories can end up with noticeably different estimated pensions.

High-3 average salary is the highest average basic pay you earned during any 3 consecutive years of service. Basic pay includes your base salary and locality pay, but it excludes bonuses, overtime, and most other additional compensation. For most federal employees the High-3 falls in the final years before retirement, since pay generally rises over a career, though that is not guaranteed in every case.

Years of creditable service is your total federal service used for annuity computation purposes, which, as covered below, can include unused sick leave even though sick leave does not count toward retirement eligibility.

The pension multiplier is where the formula gets its nuance, and it is the piece people most often estimate incorrectly. The full formula and its inputs are set out in OPM's FERS computation guidance, which is the source behind every figure on this page.

Running the formula by hand is straightforward once you have the three inputs. Below are two versions of the same hypothetical employee, shown side by side to illustrate how the multiplier changes the estimate.

The multiplier itself depends on your age and service at retirement. It is 1% of High-3 per year of service if you retire under age 62, or if you are 62 or older with fewer than 20 years of service. It rises to 1.1% per year only if you are age 62 or older with 20 or more years of service. That single threshold, 20 years of service at 62, is often worth working toward deliberately rather than by accident.

Your Minimum Retirement Age (MRA) also affects when an unreduced annuity is even available. MRA is age 55 for those born before 1948, rising in increments to age 56 for those born between 1953 and 1964, and age 57 for those born in 1970 or later. Retiring with fewer than 20 years of service and before age 60 generally carries an additional reduction of approximately 5% for each year you are under age 62, unless your agency has offered an early retirement authority that waives it.

Electing a survivor annuity for a spouse also changes the number you actually receive. A survivor election reduces the estimated annuity in the examples above; the trade-off, and why many federal employees elect it anyway, is covered in our guide to the FERS survivor benefit election.

Special provisions employees, including law enforcement officers, firefighters, and air traffic controllers, use a different multiplier entirely: approximately 1.7% of High-3 for each of their first 20 years of service, and 1% for years beyond 20. If you fall into one of these categories, treat the general examples above as illustrative only, not as your own estimate.

Unused sick leave has a narrow but real role in the FERS formula. Per OPM Benefits Administration Letter 18-103, unused sick leave is added to your years of service for annuity computation purposes, which can increase the service figure used in the formula above.

What sick leave cannot do matters just as much. It cannot be used to establish eligibility for retirement, meaning it does not help you meet the minimum age or service requirements to retire in the first place. It also is not included when calculating your High-3 average salary; that figure is based on basic pay earned, not on unused leave balances.

There is one case worth flagging directly. If you are age 62 or older with less than 20 years of actual service, but your unused sick leave brings the total to 20 years or more for computation purposes, the 1.1% multiplier applies to the full total. For employees close to that 20-year line, a sick leave balance may be the difference between the 1% and 1.1% calculation, which is worth checking before assuming which multiplier applies to you.

The FERS basic annuity is generally only one of several income sources a federal retiree draws on, and the FERS annuity supplement is often the least understood piece. OPM computes it as if you were age 62 and fully insured for Social Security: it estimates your full-career, 40-year Social Security benefit, then prorates that estimate by your FERS years of service divided by 40. In OPM's own example, an estimated full-career benefit of $1,000 with 30 FERS years produces a supplement of $1,000 times 30/40, or approximately $750 per month. The supplement is generally payable from retirement until age 62, is reduced under a Social Security-style earnings test of $1 for every $2 earned above the exempt amount, and is not available to employees who take a deferred annuity. Our guide to the FERS supplement covers eligibility and the earnings test in more detail.

Putting the pieces together: your FERS basic annuity estimate, the supplement if you qualify for it, and your own Social Security benefit generally have to work alongside whatever you draw from the TSP. How much of that TSP balance to keep in place versus roll over, and how to sequence withdrawals against the annuity, is its own decision; see our guide on TSP in retirement for that piece. The years between retirement and when required distributions begin are also frequently the lowest tax bracket a federal retiree will see, which is why many federal retirees pair a pension estimate with a look at Roth conversions rather than treating the pension in isolation.

A FERS pension estimate is a genuinely useful number, but it is one input among several rather than a complete retirement plan on its own. Our Retirement Navigation System organizes exactly this kind of decision: it walks each client through 3 levers and 9 accelerators that connect the pension, the TSP, Social Security timing, and taxes into a single picture, rather than evaluating each piece separately. Ready to see your full federal benefits picture? You can get a personalized federal benefits report that estimates your FERS pension alongside your TSP balance, Social Security timing, and overall retirement income plan.

Book a 30-minute federal benefits review to get your personalized federal benefits report started.