How to Calculate Your FERS Retirement
Calculate your FERS basic benefit, special retirement supplement, and total retirement income.
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FERS Supplement Calculator 2026
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OPM SRS formula
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Financial Disclaimer: This calculator is for informational purposes only. It is not financial advice. Contact OPM or a licensed financial advisor for official retirement benefit estimates.
How to Calculate FERS Supplement
The OPM formula takes your estimated Social Security benefit at age 62 and scales it by the fraction of a full 40-year federal career you completed. For the full retirement income picture including your FERS pension, see the FERS Retirement Calculator.
Monthly SRS = Estimated SS at 62 x (Creditable Service Years / 40)
Annual SRS = Monthly SRS x 12
Service Fraction = min(years, 40) / 40
Example: SS $2,400/mo, 28 years of service
Monthly SRS = $2,400 x (28 / 40) = $2,400 x 0.70 = $1,680/mo
Annual SRS = $1,680 x 12 = $20,160/yr
Annual SRS = Monthly SRS x 12
Service Fraction = min(years, 40) / 40
Example: SS $2,400/mo, 28 years of service
Monthly SRS = $2,400 x (28 / 40) = $2,400 x 0.70 = $1,680/mo
Annual SRS = $1,680 x 12 = $20,160/yr
The service fraction caps at 1.0 (40/40). Federal employees with 40 or more years receive the full SS estimate as their SRS; more than 40 years does not increase the supplement.
FERS Annuity Supplement Calculator: Monthly SRS by Service Years
The table below shows monthly SRS amounts at common service lengths and SS benefit levels. Find your years of service in the left column and cross-reference with your estimated age-62 Social Security benefit.
| Years of Service | SS $1,500/mo | SS $2,000/mo | SS $2,500/mo |
|---|---|---|---|
| 20 years | $750 | $1,000 | $1,250 |
| 25 years | $938 | $1,250 | $1,563 |
| 30 years | $1,125 | $1,500 | $1,875 |
| 35 years | $1,313 | $1,750 | $2,188 |
| 40 years | $1,500 | $2,000 | $2,500 |
Values are rounded. OPM uses the exact SS estimate from your SSA.gov statement in the official computation.
FERS Social Security Supplement: Earnings Test
If you work after retiring, earned income above $22,320/year (2025 threshold) reduces the SRS by $1 for every $2 earned above the limit. The table below shows the impact on a $1,500/month supplement. If you are planning how long your savings last once the SRS ends at 62, the Savings Duration Calculator models that drawdown period.
| Annual Earned Income | Above $22,320 | Annual Reduction | Net Monthly SRS |
|---|---|---|---|
| $22,320 or less | $0 | $0 | $1,500 |
| $30,000 | $7,680 | $3,840/yr | $1,180 |
| $40,000 | $17,680 | $8,840/yr | $763 |
| $50,000 | $27,680 | $13,840/yr | $347 |
| $58,320+ | $36,000+ | Full elimination | $0 |
Earnings limit adjusts each year with SSA wage index changes. TSP distributions, pension payments, rental income, and investment income are not counted as earned income for this test.
FERS Special Retirement Supplement for Law Enforcement and Firefighters
Special category employees (law enforcement officers, firefighters, and air traffic controllers) qualify for the SRS under different retirement thresholds than regular FERS employees. The SRS calculation uses the same formula; the eligibility timing differs.
| Category | Retirement Eligibility | SRS Eligible |
|---|---|---|
| Law Enforcement Officer | Age 50 + 20 yrs special OR any age + 25 yrs | Yes |
| Firefighter (FERS) | Age 50 + 20 yrs special OR any age + 25 yrs | Yes |
| Air Traffic Controller | Age 50 + 20 yrs OR any age + 25 yrs; mandatory at 56 | Yes |
| Regular FERS (MRA+30) | MRA (55-57) + 30 or more years | Yes |
| Regular FERS (age 60+20) | Age 60 + 20 or more years | Yes |
| MRA+10 | MRA + 10-29 years (reduced annuity) | No |
Special category employees use total years of creditable federal service (not just special category years) in the SRS formula. An LE officer with 20 special years and 5 prior regular federal service uses 25 total years in the calculation.
Example Calculation
Diane retires from federal service at age 58 with 32 years of creditable service. Her SSA.gov statement shows an estimated benefit of $2,200/month at age 62. She plans to work part-time earning $30,000/year. She also runs the 401k Calculator with Match to model her TSP contributions before retirement.
Estimated SS at 62$2,200/mo
Service fraction (32 / 40)0.80
Gross monthly SRS ($2,200 x 0.80)$1,760/mo
Annual gross SRS ($1,760 x 12)$21,120/yr
Part-time earned income$30,000/yr
2025 earnings limit$22,320/yr
Above limit ($30,000 - $22,320)$7,680
Earnings test reduction ($7,680 / 2)-$3,840/yr
Net annual SRS ($21,120 - $3,840)$17,280/yr ($1,440/mo)
Diane receives $1,440/month in net SRS while working part-time, down from the $1,760 she would receive if not working. The 4-year SRS window (age 58 to 62) totals approximately $69,120 in net supplement income before the supplement ends and Social Security begins.
Common Mistakes to Avoid
Using the wrong Social Security estimate
Enter your estimated SS benefit at age 62, not at full retirement age (67) or age 70. Using the higher delayed-retirement figure overstates the SRS by 25-30 percent.
Forgetting the earnings test
If you work after retiring and earn more than $22,320/year (2025), your supplement is reduced by $1 for every $2 above the limit. Plan earned income carefully in the years before 62.
Expecting the supplement to continue past 62
The SRS stops automatically at age 62 regardless of whether you file for Social Security. Do not count on it beyond that age in your income projections.
Counting MRA+10 retirement as eligible
If you retire under MRA+10 (MRA with 10-29 years of service), you do not qualify for the supplement. Only immediate, unreduced annuities trigger SRS eligibility.
Forgetting FEHB premiums reduce your net check
Federal Employee Health Benefits premiums come out of your annuity in retirement, just as they did from your paycheck. Budget for this when calculating net monthly income.
Frequently Asked Questions
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Sources & References
1
OPM: FERS Special Retirement Supplement ↗
Official OPM page on the SRS, including eligibility criteria, the calculation formula, and earnings test rules.
2
Social Security Administration: my Social Security ↗
Primary source for the age-62 SS benefit estimate used in the SRS formula. Workers create an account to obtain their personalized statement.
3
OPM CSRS and FERS Handbook ↗
OPM's authoritative handbook covering the FERS Retiree Annuity Supplement in Chapter 51, including eligibility, computation, earnings test, and suspension rules.
HR
Hassaan Rasheed
Developer and Researcher, CalculatorFlux
Researches and verifies the formulas, methodology, and source data behind each calculator on CalculatorFlux. All tools are built and checked against the cited references before publication.
Last updated: May 2026