FERS Disability Annuity Calculation: The 60/40 Formula Explained

Year 1: 60% of Your High-3 Average Salary

For the first 12 months of your FERS disability annuity, you receive 60% of your High-3 average salary, minus 100% of any Social Security Disability Insurance (SSDI) benefit you receive. Your High-3 is the average of your highest three consecutive years of basic pay — for most federal employees, this is their final three years of service.

If your High-3 average is $85,000 and you receive $1,800 per month in SSDI ($21,600 annually), your Year 1 calculation looks like this:

• 60% × $85,000 = $51,000
• Minus 100% of SSDI: $51,000 − $21,600 = $29,400 annually
• Monthly gross: approximately $2,450

If your SSDI application is pending (which is common — Social Security decisions often take longer than OPM's), OPM pays the full 60% without the offset until SSDI is awarded. Once SSDI approval arrives, OPM retroactively adjusts for the overlap period.

Year 2 and Beyond: 40% of Your High-3

Starting in your second year on disability retirement and continuing until age 62, the formula shifts:

• 40% of your High-3 average salary
• Minus 60% of your SSDI benefit

Using the same numbers:

• 40% × $85,000 = $34,000
• Minus 60% of SSDI: $34,000 − $12,960 = $21,040 annually
• Monthly gross: approximately $1,753

The drop from Year 1 to Year 2 is significant. This is the financial reality that makes planning during the application phase so important — you need to know what your actual monthly income will be, not just the percentage formulas.

There's a floor built into the formula: your annuity can never be less than the amount you would have received under the standard FERS computation (1% or 1.1% × years of service × High-3). For employees with shorter service histories, the disability formula almost always exceeds this floor. For those with 25+ years, run both calculations.

The Age 62 Recalculation

At age 62, OPM recalculates your disability annuity as a regular FERS service retirement. All the years you spent on disability retirement count as active creditable service for that calculation.

The conversion uses the standard FERS formula: 1% (or 1.1% if you have 20+ years of service and retire at 62 or later) × total creditable service years × your High-3 at the time of disability retirement, adjusted for cost-of-living increases.

For someone who went on disability retirement at age 45 with 15 years of service, by age 62 they'd have 32 years of creditable service. At the 1.1% multiplier: 1.1% × 32 × adjusted High-3. The years on disability retirement accumulate automatically — you don't need to make deposits or buy back time.

What the SSDI Offset Does Not Include

The FERS-to-SSDI offset under 5 U.S.C. § 8452 is a separate mechanism from the now-repealed Windfall Elimination Provision (WEP) and Government Pension Offset (GPO). The Social Security Fairness Act (H.R. 82, signed January 5, 2025) eliminated WEP and GPO for benefits payable January 2024 onward. But the FERS statutory offset against SSDI remains fully active — it's a different provision with a different legal basis.

This distinction matters because online forums regularly conflate the two. Your FERS disability annuity is still reduced by your SSDI benefit under the 60/40 formula. What changed is that your Social Security retirement, spousal, or survivor benefits are no longer reduced by WEP or GPO if you also receive a FERS or CSRS pension.

Earned Income Limits After Approval

Under 5 CFR 844.402, FERS disability annuitants under age 60 can earn income from private-sector employment. However, if your net earned income in any calendar year reaches 80% of the current rate of basic pay for the position you held before retirement, OPM considers your earning capacity restored. Your disability annuity terminates the following June 30.

OPM monitors this through tax records, and the 80% threshold is measured against the current pay rate for your former position — not what you were earning when you left. If that position's salary has increased since your retirement, the threshold rises accordingly.

Running Your Own Numbers

Before filing, you need concrete projections for both Year 1 and Year 2 income. Gather your High-3 average from your most recent SF-50 series, estimate your likely SSDI benefit using SSA's online calculator, and run the formulas above. The FERS Disability Retirement for Mental Health Conditions guide includes a financial planning worksheet that walks through the full calculation with your actual numbers, including the SSDI offset scenarios and the age 62 conversion estimate.

Knowing what your annuity will actually be — not just the percentage — is what lets you make informed decisions about when to file, how to bridge the gap during OPM's review period, and whether your household can sustain the Year 2 income drop.

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