FERS Disability Retirement Calculator

How this is calculated

A FERS disability annuity moves through three formulas, and only the first of them is the one people are told about. Each is a separate subsection of 5 U.S.C. § 8452:

1. The first 12 months

annuity = 60% × high-3 − 100% of SSDI

§ 8452(a)(1)(A) sets the rate; § 8452(a)(2) takes the whole of any Social Security disability benefit back off it. If SSDI is larger than the 60%figure, the subtraction stops at zero rather than going negative — the statute says an annuity “may not be reduced below zero by reason of this paragraph” — and the floor below then takes over.

2. Month 13 until 62

annuity = 40% × high-3 − 60% of SSDI

§ 8452(a)(1)(B). This is the phase where the floor most often decides the answer, because 40% of high-3 is not a large number: an employee with 30 years of service has already earned 30% of high-3 under the ordinary formula, and 40% less 60% of a $2,000 SSDI benefit comes to less than that.

3. The floor underneath both

floor = high-3 × 1%× years of service

§ 8452(d)(1) says the annuity “shall not be less than the amount of an annuity computed under section 8415 (excluding subsection (h))” — the annuity your service earned, with the parenthesis removing the 5%-a-year age reduction that a voluntary early retirement would carry. That is worth stating plainly: no age reduction applies to a disability retirement, at any age. The 1.1%accrual rate is a different matter — § 8415(i) requires age 62 with 20 years, so before the recomputation it cannot be met.

4. The recomputation at 62

On the day you turn 62, § 8452(b) throws all of the above away and computes an ordinary FERS annuity, with two adjustments in your favour: the time you spent drawing the disability annuity is creditable service ((b)(2)(B)(i)), and your average pay is increased by every cost-of-living adjustment paid since you retired ((b)(2)(B)(ii)). The Social Security offset ends here too, because it lives in subsection (a) and this annuity is computed under (b).

The service credit is the finding this tool exists for. Someone who leaves at 45 with 15 years reaches 62 with 32 years of creditable service, which is over the 20-year test, so the accrual factor rises to 1.1% on the whole of it. It is also not a guaranteed raise: 1.1% of 32 years is 35.2% of high-3, less than the 40%phase it replaces, and nothing in § 8452 preserves the higher figure.

Eligibility, in one paragraph

§ 8451(a)(1)(A) requires 18months of civilian service creditable under § 8411, and a disease or injury that leaves you unable “to render useful and efficient service” in your position — your position, not any work at all, which is a materially lower bar than Social Security’s. If you are already eligible to retire voluntarily under § 8412 — age 62with 5 years, age 60 with 20, or your minimum retirement age with 30 — then § 8452(c) takes you out of the disability formula entirely and pays the annuity you earned. MRA+10 is deliberately excluded from that list by the words “other than subsection (g)”, so an employee with only MRA+10 eligibility stays on the disability formula, and keeps the floor computed without the age reduction.

What this does not model

• Whether OPM will approve the application. That is the hard part of a disability retirement, and it is a medical and evidentiary question this tool has nothing to say about.
• Cost-of-living adjustments.Every figure is in today’s dollars. A disability annuitant is paid COLAs from the start at any age — the under-62 freeze in § 8462(c)(3) binds annuitants under §§ 8412, 8413 and 8414 and a disability annuitant is not on that list — and those adjustments also raise the average pay used in the recomputation at 62. Both effects make the real figures larger than the ones shown here, and both depend on inflation nobody can forecast.
• The earnings test. A disability annuity stops if you recover, if you are restored to earning capacity (income of 80% or more of the current rate for your old position), or, before age 62, if you are found recovered on a medical review. Those are the conditions of keeping the annuity, not part of computing it.
• Survivor elections and insurance. The figures are unreduced. A survivor annuity election takes a further percentage off all of them.
• CSRS disability retirement, which is a different computation with a guaranteed minimum of its own and no Social Security offset.
• Workers’ compensation. FECA benefits and a FERS annuity cannot be drawn for the same period; you elect between them. Nothing here models that choice.
• Sick leave.Unused sick leave is added to service in the ordinary § 8415 computation, so it reaches the floor and the recomputation at 62. This tool takes service as a single figure — convert your hours with the sick leave calculator and include them.

Sources

• 5 U.S.C. § 8452 — the whole computation: the 60%/40% rates in (a)(1), the Social Security offset and its zero stop in (a)(2), the recomputation at 62 in (b), the exemptions in (c), and the earned-annuity floor in (d)(1).
• 5 U.S.C. § 8451 — eligibility: 18months of civilian service, and the “useful and efficient service” standard.
• OPM CSRS/FERS Handbook, Chapter 60 — Disability Retirement (PDF) — OPM’s own worked examples of the offset and the recomputation.
• 5 CFR Part 844 — the regulations, including 844.201(b): no payment is authorised until an SSDI application has been filed or SSA has said you are not eligible.
• 5 U.S.C. § 8415 — the ordinary FERS formula the floor and the recomputation are both built from, including the 1.1% factor at 62 in (i) and the age reduction in (h) that a disability retirement never carries.

Last reviewed: August 2026