FEHB and Medicare at 65: the coordination decision every DC federal retiree faces.

About 14% of working DC residents are federal employees. Add federal annuitants in retirement, plus spouses and survivors, and the share of DC households with a federal-benefits coverage history is the highest in the country. For these families, the question that arrives at age 65 isn’t “should we sign up for Medicare^?? ” (yes, almost always for Part A; usually for Part B), it’s “how should Medicare coordinate with FEHB?” That question has three plausible answers, and they have meaningfully different consequences for premium costs, provider access, and out-of-pocket exposure for the rest of retirement.

The choice gets harder because the federal benefits ecosystem doesn’t give annuitants a ready-made answer. OPM produces clear documentation of each program separately; the coordination across programs is something the retiree (and the adult children helping them) has to assemble. This piece walks through the FEHB-Medicare architecture, the three coordination paths, and the four questions to settle before the Medicare Initial Enrollment Period closes.

The federal benefits architecture, briefly

The Federal Employees Health Benefits program (FEHB) is a defined-contribution health insurance program administered by the Office of Personnel Management.1 Active federal employees and eligible annuitants choose from a menu of FEHB plans (Blue Cross Blue Shield, GEHA, several HMOs and POSs); the government pays approximately 70% of the premium for both active employees and retirees.

The 5-year rule for retirees: to carry FEHB into retirement, the employee must have been continuously enrolled in FEHB (or covered as a family member) for the five years immediately preceding retirement. This rule catches some late-career federal hires who haven’t accumulated five years; for most career federal employees, the rule is satisfied automatically.

Continuing FEHB in retirement preserves the federal government’s premium contribution for life. The retiree pays approximately 30% of the premium — typically $200–$500/month for self-only coverage in 2026 depending on plan choice — with the government covering the rest. This is the benefit most federal retirees consider their most valuable.

How Medicare fits in

At 65, federal annuitants with the typical Medicare- payroll-tax history (40 quarters or more, which most federal employees have through prior private-sector work, military service, or federal CSRS offset/FERS contributions) are eligible for Medicare^? Parts A and B.2

• Part A (hospital insurance): Premium-free for those with the qualifying work history. Almost always worth enrolling in at 65.
• Part B (medical insurance): Base premium $185/month in 2026 for most enrollees, higher for higher-income annuitants under the IRMAA^? surcharge system. The Part B decision is the consequential one.
• Part D (prescription drug): Generally redundant if the retiree has FEHB prescription coverage; some retirees enroll anyway for the 2025+ out-of-pocket cap.5
• Part C (Medicare Advantage): Generally not the right choice for federal annuitants who continue FEHB — the architectures don’t pair well.

The three coordination paths

Path 1: Keep FEHB and enroll in Medicare A+B

The path OPM and most federal-benefits counselors recommend by default. The retiree:

• Stays in their FEHB plan (continuing the federal premium contribution);
• Enrolls in Medicare Part A at 65 (premium-free);
• Enrolls in Medicare Part B at 65 (paying the $185+/month premium);
• Does not separately enroll in Part D, Medigap, or Medicare Advantage.

Under this path, Medicare becomes the primary payer for most services (Part A pays first for hospital; Part B pays first for physician and outpatient care), and FEHB becomes the secondary payer.3FEHB picks up most of Medicare’s cost-sharing — the Part A and Part B deductibles, coinsurance, and the 20% Part B coinsurance that hits Medigap-only enrollees hard.

The retiree pays:

• The FEHB premium share (about 30% of plan cost);
• The Medicare Part B premium ($185+/month);
• Minimal out-of-pocket costs because the two coverages stack.

Total typical 2026 cost for a self-only retiree on Path 1: roughly $400–$700/month combined, producing a benefit package that’s richer than almost any single-source health insurance available in the United States.

Path 2: Keep FEHB, enroll in Part A only

The retiree continues FEHB but does not enroll in Part B. Some annuitants choose this path for two reasons:

• Cost. Avoiding the Part B premium saves $2,220/year (or substantially more at higher income levels with IRMAA surcharges of $500+/month).
• Provider network. A retiree with a FEHB plan offering broad network access who is comfortable with FEHB as primary may not feel the need for the Medicare Part B layer.

The downside is structural: a retiree who declines Part B at 65 and later wants it faces a permanent late-enrollment penalty of 10% per year delayed, and can only enroll during the General Enrollment Period (January 1–March 31, coverage starting that July). The decision to defer Part B isn’t easily reversible.

Path 3: Drop FEHB, rely on Medicare with Medigap

The retiree exits FEHB entirely. Coverage becomes:

• Medicare Part A;
• Medicare Part B;
• A standalone Medigap (Medicare Supplement^?) policy (typically Plan G);
• A standalone Medicare Part D plan.

This path is rarely the right answer for federal retirees who qualify for FEHB. The reason: dropping FEHB means the retiree gives up the federal government’s premium contribution permanently and cannot re-enroll. The Medigap+Part D combination may be cheaper in some years but is rarely cheaper over a 20-year retirement, and the trade is irreversible.

The few situations where Path 3 is worth modeling: retirees whose FEHB premium is unusually high (specific plan choices), retirees with strong preference for a particular Medigap plan’s structure, or retirees who anticipate moving abroad (FEHB has limited overseas coverage).

The IRMAA surcharge layer

Higher-income federal annuitants face significant additional Part B premiums under the Income-Related Monthly Adjustment Amount (IRMAA^?) system. IRMAA looks at the modified adjusted gross income from the tax return filed two years prior (so the 2026 IRMAA tier is based on 2024 income) and adds surcharges in five income tiers.

For high-income DC federal annuitants (think senior executives, judges, members of Congress), the IRMAA surcharge can add several hundred dollars per month to the Part B premium. The combined IRMAA-adjusted Part B + FEHB premium under Path 1 can exceed $1,000/month for very high earners. This is the fact pattern where Path 2 (skip Part B) becomes more interesting on cost — though usually not enough to override the structural advantages of Path 1.

IRMAA is appealable for life-changing events (job loss, divorce, marriage, death of spouse). The SSA-44 form is the operative appeal document; a successful appeal can reduce or eliminate IRMAA for a given year. For DC federal retirees who left high-paying positions in the last two tax years, the appeal is often worth filing.

What FEHB does that Medicare doesn’t

The strongest argument for keeping FEHB layered with Medicare is that FEHB covers things Medicare generally doesn’t:

• Vision, dental, and hearing. Medicare excludes these; many FEHB plans include modest coverage.
• Routine physicals and wellness exams. Medicare covers an annual wellness visit but not traditional comprehensive physicals; FEHB plans typically cover both.
• Cost-sharing for Medicare-covered services. Medicare Part A and B have substantial cost-sharing (Part A deductible $1,632/admission in 2024, Part B 20% coinsurance with no annual cap). FEHB as secondary covers most of this.
• Some prescription coverage. Most FEHB plans have meaningful prescription coverage, often as good as or better than standalone Medicare Part D.

What FEHB doesn’t cover — for any plan, for any annuitant — is long-term custodial care. That’s the gap the Federal Long Term Care Insurance Program (FLTCIP) was designed to fill, and it’s a separate analysis entirely.4

The Part D question

The 2025 introduction of the Medicare Part D annual out-of-pocket cap ($2,000 in 2025, ~$2,100 in 2026) changed the standalone Part D math.5 For federal retirees with FEHB prescription coverage, the question is now:

• Does my FEHB plan have a comparable OOP cap on prescriptions? Many do; some don’t.
• Are my drugs on both the FEHB formulary and a Part D formulary? If a specific high-cost drug isn’t covered well by FEHB, adding Part D may be worth the additional premium.
• Do I take any catastrophic-cost specialty drugs? The $2,100 Part D cap is most valuable for beneficiaries facing $10,000+/year out-of-pocket on a single drug.

For most federal retirees on standard medication regimens, FEHB prescription coverage alone is sufficient. For those with specialty drug regimens, adding Part D may be worth the additional premium — though most don’t need it.

The four questions to settle before 65

1. Are you continuing FEHB into retirement? Confirm the 5-year-rule satisfaction. If yes, the default coordination decision is to enroll in Medicare A+B and let the two layer (Path 1). If not, the analysis is different and outside the scope of this article.
2. What is your IRMAA exposure?Pull the modified adjusted gross income from the tax return two years before your 65th birthday year. If you’re in an IRMAA tier, the Part B premium math changes substantially; if you have grounds for an SSA-44 appeal (job loss, divorce, etc.), file it.
3. What does your FEHB plan’s Medicare-coordination structure look like? Some FEHB plans (notably some Blue Cross plans and GEHA plans) waive deductibles and copays for Medicare-primary enrollees. Others don’t. The specific FEHB plan you have may favor Path 1 strongly; switch plans during Open Season if a better-coordinating option is available.
4. Have you addressed long-term care separately?FEHB doesn’t cover it. FLTCIP may be available. Self-funding, family- funding, and (eventually) Medicaid LTC are the alternatives. The FEHB-Medicare decision doesn’t resolve this question; it has to be handled in parallel.6

The bottom line

For most DC federal retirees, the right FEHB-Medicare coordination is Path 1: keep FEHB, enroll in Medicare A and B, let the two layer. That’s also the path OPM’s benefit counselors recommend by default, and it produces the richest combined coverage available in the US health-insurance market. The exceptions are specific: very high-income annuitants where IRMAA tips the math, retirees with unusually rich FEHB plans where Part B becomes redundant, and retirees moving abroad. For families helping a parent through the decision, the most useful move is to read the specific FEHB plan’s Medicare-coordination terms, model the IRMAA exposure, and confirm enrollment in Part B during the Initial Enrollment Period rather than relying on a late-enrollment correction. The penalty for waiting is permanent. The benefit of choosing Path 1 at 65 lasts a lifetime.