FEHB Calculator: How to Use It
The government subsidy that keeps your FEHB premiums manageable during your career follows you into retirement. This calculator shows what it actually costs, how it compounds over 20 years, and how Medicare changes the math at 65.
What this calculator does
The FEHB Calculator shows your monthly premium for a given plan and coverage tier, projects what that premium will likely look like over 20 years with premium inflation, calculates your premium as a percentage of your FERS annuity, models Medicare Part B coordination at age 65, and, for self-only coverage, compares your premium with the 2026 average ACA marketplace benchmark premium for a 60-year-old.
The marketplace comparison tends to surprise people. A federal retiree paying $289.83 per month for BCBS Basic self-only coverage gets $703.65 per month from the government toward a $993.48 total premium. On the marketplace, KFF's 2026 national average benchmark silver premium is $625 a month for a 40-year-old. Scaled to age 60 with CMS's default age curve (2.714 / 1.278), that's about $1,327 a month before any premium tax credit, and state averages vary widely.
What each input means
Plan selection
The calculator includes three of the most widely used FEHB plans: GEHA Standard ($187.95 per month self-only in 2026), BCBS Basic ($289.83), and BCBS Standard ($408.02). These are OPM's 2026 enrollee-share premiums for annuitants and non-postal employees. Postal retirees moved to the PSHB Program in January 2025 and pay different rates. If you're in a regional HMO or another plan, pick the closest premium here or check OPM's plan comparison tool.
Coverage tier
Self Only, Self Plus One, and Self and Family. Self Plus One covers you and one designated family member, introduced in 2016. It typically costs less than Self and Family when you have a spouse but no dependent children. Confirm which tier you're enrolled in before entering any numbers. The premium difference between Self Only and Self and Family can be $250 to $300 per month depending on the plan.
FERS annual annuity
Used to calculate FEHB premium as a percentage of your pension. This is your gross annual annuity before taxes and any deductions. Enter the pre-tax figure. The output shows what share of your pension check goes toward health coverage, which helps with cash flow planning when the FERS annuity is your primary income source.
Current age and years in retirement
Age is used to determine when Medicare Part B coordination kicks in at 65. Years in retirement drives the 20-year premium projection. The projection applies your chosen premium inflation rate (the historical average is 5 to 6 percent annually for FEHB) to show the cumulative cost trajectory.
Medicare Part A and Part B enrollment
Checking Medicare Part A signals that hospital coverage is active. Almost all federal retirees over 65 have Part A at no cost. Checking Part B adds the 2026 standard premium of $202.90 per month and models the coordination: with Part B active, Medicare becomes the primary payer for most covered services and FEHB fills the gaps. Your FEHB premium stays the same once Medicare starts; the calculator adds Part B on top. That combined cost leads some retirees to switch to a lower-cost FEHB plan at open season.
Premium inflation rate
Controls the 20-year projection. The default is 5 percent, which reflects FEHB's historical average annual premium increases. You can lower it to 3 percent for an optimistic scenario or raise it to 7 percent for a conservative one. The cumulative cost figure changes substantially across these assumptions, which is the point of adjusting it.
Understanding the outputs
The monthly premium figure is what will be deducted from your FERS annuity check each month. The annual premium is that number times 12. The percentage of pension shows how much of your retirement income goes to health coverage. For a retiree with a $25,000 annual FERS pension paying $310 per month for BCBS Standard self-only, that's nearly 15 percent of pension income. Understanding this ratio matters when sizing your retirement income target.
The 20-year total cost with inflation shows the cumulative FEHB outlay if premium inflation continues at the chosen rate. The marketplace box (self-only only) compares this year's FEHB premium with the 2026 benchmark figure above. It doesn't project marketplace prices forward, because there's no published forecast to base that on.
The Medicare coordination section shows combined monthly costs when both Part B and FEHB are active, and compares that to FEHB alone. For some retirees, particularly those who switch to a cheaper FEHB plan after enrolling in Part B, the combined cost is actually lower than FEHB alone with a more expensive plan.
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Frequently asked questions
What is the 5-year rule for keeping FEHB in retirement?
Continuous FEHB coverage for the five years immediately before your annuity starts, or since your first eligible opportunity if less than five years. Time covered as a family member on someone else's FEHB enrollment counts. You must also be enrolled when you retire and be entitled to an immediate annuity, which includes MRA+10. If you postpone an MRA+10 annuity, you can re-enroll when it starts. Miss the window and FEHB generally ends at retirement.
How much does FEHB cost in retirement compared to when I was working?
The gross premium is identical. The government still pays roughly 72% of the weighted average premium. What changes is the tax treatment: active employees pay with pre-tax payroll deductions, retirees pay from their annuity on an after-tax basis. The dollar amount is the same; the effective after-tax cost is slightly higher in retirement.
Should I enroll in Medicare Part B at 65 if I have FEHB?
Most federal retirees enroll in Part A at no cost and skip Part B initially. FEHB alone provides solid coverage. Part B costs $202.90 per month in 2026 at the standard rate. It pays off when ongoing medical costs are significant: Medicare becomes primary, FEHB fills gaps, and out-of-pocket costs can drop enough to justify the premium. Healthier retirees often skip Part B for years or indefinitely.
What FEHB plans does the calculator include?
GEHA Standard ($187.95 per month self-only in 2026), BCBS Basic ($289.83), and BCBS Standard ($408.02), from OPM's 2026 premium table. For other plans, look up your premium in OPM's plan comparison tool; this calculator covers these three. Regional HMOs may be cheaper in areas where they operate. Check OPM's plan comparison tool each open season for current rates in your zip code.
What does the 20-year premium projection tell me?
FEHB premiums have increased 5 to 7 percent annually on average. The projection shows what the same plan likely costs at years 1, 5, 10, and 20 of retirement, and the total cumulative outlay. For self-only coverage, the calculator also puts your FEHB share next to the 2026 average ACA benchmark silver premium for a 60-year-old before tax credits (about $1,327 a month).