How to Calculate Your FERS Retirement Pension: Formula, Multipliers, and Worked Examples

You have 28 years of federal service, your High-3 salary is $112,400, and you are trying to decide whether to retire at 60 or wait until 62. That two-year difference changes your pension multiplier from 1.0 percent to 1.1 percent, which adds $3,147 per year for life. Over a 25-year retirement, that is nearly $79,000 in additional pension income. The decision is not obvious because those two extra years also mean two more years of TSP contributions and salary. But you need the actual numbers to compare. Use our FERS Retirement Calculator to model both scenarios with your real service history and salary.

What Is the FERS Pension Formula?

The Federal Employees Retirement System uses a three-part formula for the basic annuity:

FERS Annual Pension = High-3 Average Salary x Years of Creditable Service x Multiplier

The multiplier is 1.0 percent for most retirees. It increases to 1.1 percent if you retire at age 62 or later with at least 20 years of creditable service. Both conditions must be met. A 61-year-old with 30 years of service gets the 1.0 percent multiplier. A 62-year-old with 20 years gets 1.1 percent.

According to the Office of Personnel Management, this formula has been unchanged since FERS was enacted in 1986. The pension replaces approximately 30 to 35 percent of your pre-retirement income, with Social Security and TSP filling the remaining gap to reach the 70 to 80 percent replacement rate that financial planners recommend.

Understanding Your High-3 Salary

Your High-3 is the average of your highest 36 consecutive months of basic pay. For most federal employees, this is the final three years of service, but it can be earlier if you had a higher-paying position earlier in your career.

Basic pay includes your GS base salary plus locality pay. It excludes overtime, bonuses, awards, and premium pay. If you are a GS-13 Step 5 in the Washington DC locality area, your 2026 basic pay is $122,198 ($104,898 base plus $17,300 locality). That is the number that goes into your High-3 calculation.

To calculate your High-3, add your basic pay for each of the 36 highest consecutive months and divide by 36. If you received a step increase or promotion during that period, the higher pay rate is included for the months after the increase.

Step-by-Step Example

Consider a GS-12 employee in the Rest of U.S. locality area who plans to retire at age 62 with 30 years of service. Their salary history for the final three years:

• Year 1 (age 59-60): GS-12 Step 8, $98,700 base plus 17.51 percent locality = $116,003
• Year 2 (age 60-61): GS-12 Step 9, $101,520 base plus 17.51 percent locality = $119,289
• Year 3 (age 61-62): GS-12 Step 10, $104,400 base plus 17.51 percent locality = $122,684

High-3 average: ($116,003 + $119,289 + $122,684) / 3 = $119,325

Annual pension: $119,325 x 30 x 0.011 = $39,377

Monthly pension: $3,281

If this employee retired at 60 instead of 62 with the same years of service, the multiplier would be 1.0 percent: $119,325 x 30 x 0.010 = $35,798. The 1.1 percent multiplier adds $3,579 per year, or $89,475 over a 25-year retirement.

The 1.0% vs 1.1% Multiplier Decision

The decision to wait until 62 for the enhanced multiplier depends on what you lose by staying two extra years versus what you gain.

Waiting to 62 costs you two years of pension payments but gains you the higher multiplier, two years of salary, and two years of TSP contributions. For most federal employees, the math favors waiting if health and job satisfaction permit it.

TSP Contributions and the 5% Match

Your TSP balance is the second leg of the FERS three-part system. The federal government matches contributions up to 5 percent of basic pay: a 1 percent automatic agency contribution plus a dollar-for-dollar match on the first 3 percent and a 50-cent match on the next 2 percent.

The Social Security Administration announced a 2.8 percent COLA for 2026, which applies to FERS pensions for retirees age 62 and older. The 2026 TSP elective deferral limit is $24,500 for employees under age 50. Employees aged 50 and older can make catch-up contributions of $7,500, bringing their total to $32,000. Under SECURE 2.0, employees aged 60 to 63 have a super catch-up of $11,250, for a total of $35,750.

A common mistake is front-loading TSP contributions so heavily that you hit the annual limit before December. The agency only matches on pay periods where you contribute. Spread contributions evenly across all 26 pay periods to capture the full match every time.

The FERS Supplement

The FERS Supplement is a temporary bridge payment available to retirees who retire before age 62 with at least 30 years of service (or at MRA with 30 years). It approximates the Social Security benefit you would receive at 62 and stops when you turn 62 and become eligible for actual Social Security.

The formula:

FERS Supplement = (Years of FERS Service / 40) x Estimated Social Security Benefit at 62

For an employee with 30 years of service and an estimated Social Security benefit of $2,200 per month at 62: (30 / 40) x $2,200 = $1,650 per month. That is $19,800 per year in additional retirement income until age 62.

The supplement is subject to an earnings test. In 2026, if your post-retirement earnings exceed $24,480, the supplement is reduced by $1 for every $2 earned above the limit.

Common FERS Calculation Mistakes

Using locality pay incorrectly in High-3. Locality pay is included in High-3. Overtime, bonuses, and awards are not. Some employees mistakenly include premium pay or exclude locality pay, both of which produce incorrect pension estimates.

Forgetting the 1.1% multiplier requirement. Both conditions must be met: age 62 or older AND 20 or more years of service. A 62-year-old with 18 years of service still gets the 1.0 percent multiplier.

Overestimating the FERS Supplement. The supplement is based on your estimated Social Security benefit at 62, not your final salary. Check your Social Security statement for the actual estimate rather than guessing.

Not accounting for survivor benefit reduction. If you elect a full survivor benefit for your spouse, your pension is reduced by 10 percent. A 50 percent survivor benefit reduces your pension by 5 percent.

Related Tools on ProfessionCalculators.com

To verify your current pay before calculating your High-3, use the GS Pay Scale Calculator with 2026 locality rates. State and local government employees with defined benefit pensions can use the Public Pension Benefit Calculator for similar calculations with their plan's specific multiplier. For a broader look at federal employment math, the GSA Per Diem Calculator handles TDY travel reimbursement with 2026 rates.

Frequently Asked Questions

Does locality pay count toward my High-3 salary?

Yes. Locality pay is part of basic pay for FERS purposes and is included in the High-3 calculation. Overtime, bonuses, awards, and premium pay are excluded. Only your GS base salary plus locality adjustment counts.

How much does the 1.1% multiplier add to my pension?

On a 30-year career with a $120,000 High-3, the 1.1% multiplier produces $39,600 annually versus $36,000 at 1.0%. That is $3,600 more per year, or $90,000 over a 25-year retirement. The enhancement applies only if you retire at 62 or older with at least 20 years of service.

What is the maximum TSP contribution for 2026?

The 2026 elective deferral limit is $24,500 for employees under 50. Employees 50 and older can contribute $32,000 with catch-up. Employees aged 60 to 63 can contribute $35,750 under the SECURE 2.0 super catch-up provision. The agency match of up to 5 percent is separate from these limits.

How is the FERS Supplement calculated?

The supplement equals your years of FERS service divided by 40, multiplied by your estimated Social Security benefit at age 62. For 30 years of service and a $2,200 estimated monthly Social Security benefit, the supplement is $1,650 per month. It stops at age 62 when you become eligible for actual Social Security.

Should I verify my FERS estimate with OPM?

Yes. These calculations are directionally accurate for planning, but actual benefits depend on your specific service history, retirement date, deposit payments for military time, and OPM adjudication. Request a retirement estimate from your agency HR and verify with OPM retirement services before making irrevocable decisions.

Conclusion

Your FERS pension is the most predictable part of your retirement income because the formula is fixed by law. The variables you control are your retirement date, TSP contribution rate, and High-3 salary. If you are within five years of retirement, model your pension at both your current age and at 62 to see the multiplier difference. Verify your High-3 with your agency HR, confirm your TSP contribution rate captures the full 5 percent match, and request an official OPM retirement estimate. The math is simple once you have the numbers. The planning is what takes time.