FEHB in Retirement: Medicare Coordination, the Part B Decision, and IRMAA Planning for Federal Employees

Federal retirees have access to one of the best employer-sponsored health systems in the world — the Federal Employees Health Benefits Program. But at age 65, you face a layered decision: keep FEHB alone, add Medicare Part B, or restructure coverage entirely. And if you're drawing from your TSP in retirement, the size of those withdrawals can quietly increase your Medicare premiums through IRMAA by thousands of dollars per year.

What FEHB is — and why it's unusually valuable in retirement

The Federal Employees Health Benefits Program covers about 8 million federal employees, retirees, and their families. Unlike private-sector health benefits that typically end at retirement or become expensive COBRA, FEHB continues into retirement with the same government contribution you received as an employee.

In 2026, the government pays up to 72% of the weighted average premium — a maximum government contribution of $324.76/month for Self Only, $711.17 for Self Plus One, or $778.03 for Self and Family.¹ That subsidy doesn't disappear when you retire. It continues as long as you remain an annuitant enrolled in FEHB.

The practical value: a federal retiree enrolled in a mid-tier FEHB plan pays something in the neighborhood of $150–$250/month for self-only comprehensive coverage that would cost $600–$900/month or more on the individual market. That gap is real money compounded across 20–30 years of retirement.

The 5-year rule: qualifying to carry FEHB into retirement

Continuous enrollment in FEHB is not automatic. To carry FEHB into retirement, you must meet one condition: be enrolled in FEHB for the five years of service immediately before the date you retire — or, if you've been a federal employee for fewer than five years, for all of your federal service since your first opportunity to enroll.²

Key nuances from OPM:

• Time spent covered as a family member under a spouse's FEHB enrollment counts toward your 5 years — you don't have to be the primary enrollee.
• TRICARE coverage also counts toward the 5-year requirement as long as you are enrolled in FEHB on your retirement date.
• Breaks in federal service (e.g., a gap between jobs) don't reset the 5-year clock, provided you re-enrolled in FEHB within 60 days of returning to federal service.
• OPM can waive the requirement in rare cases of equity or hardship.

How FEHB premiums work in retirement

Once you retire, your FEHB premium is deducted from your annuity payment rather than from a paycheck. The government share stays the same; you pay the employee share as usual.

One important tax difference: active federal employees pay FEHB premiums pre-tax under a premium conversion arrangement. Federal retirees pay FEHB premiums after-tax from their annuity — so the tax treatment changes at retirement. (Exception: some employees who return to part-time federal work while receiving an annuity may have pre-tax treatment restored in certain situations.)

Premium changes take effect January 1 each year. For 2026, the average FEHB premium increase was 10.2% overall, with the enrollee share rising about 12.3%.¹ Plan selection during Open Season (November of each year) is the primary lever retirees have to manage premium costs.

Medicare at 65: the decision federal retirees face

At age 65, you become eligible for Medicare. This is where FEHB coverage gets more complex — and where the decisions have the largest long-term cost consequences.

Medicare Part A: take it, it's free

Most federal employees qualify for premium-free Medicare Part A (hospital insurance) after 40 quarters of Medicare-taxed work. Federal employees hired after 1983 pay Medicare taxes. If you were hired before 1983, check with SSA — you may have fewer quarters, and Part A premiums can reach $518/month in 2026 for those with no Medicare work history.

There's no reason to delay Part A enrollment for most federal employees. It's free, adds a secondary payer for hospitalizations, and won't increase your FEHB premiums. Enroll when you become eligible at 65.

Medicare Part B: the real decision

Medicare Part B (outpatient, physician, lab coverage) costs $202.90/month in 2026 as the base premium — before any IRMAA surcharges.³ For a couple where both are enrolled in Part B, that's $405.80/month on top of FEHB premiums.

The decision is whether to enroll in Part B or decline it. You have three real options:

Why the FEHB + Part B combination often wins

When Medicare Part B is primary and FEHB is secondary, most FEHB plans waive or sharply reduce cost-sharing on covered services. For example, BCBS Federal Employee Program (Standard and Basic options) waive copays, coinsurance, and deductibles on most outpatient services when Medicare pays primary. The combined coverage creates a near-zero out-of-pocket experience for most medical care.

The break-even math: if you're prone to even moderate medical utilization — a few specialist visits, lab work, an outpatient procedure — the Part B premium pays for itself through FEHB cost-sharing that doesn't apply. For someone with chronic conditions or who sees multiple specialists regularly, FEHB + Part B is usually the financially optimal choice.

The late enrollment penalty: why you shouldn't delay Part B without a plan

If you decline Medicare Part B at 65 and later want to enroll, you face a permanent late enrollment penalty: 10% per 12-month period you were eligible but not enrolled. Wait 5 years: your Part B premium is permanently 50% higher — for life.

FEHB provides a Special Enrollment Period (SEP) exception: if you are enrolled in FEHB at 65 and choose to delay Part B, you can enroll later without the penalty — but only under specific OPM-coordinated enrollment rules. This is not a blanket waiver; the process requires coordination and proper documentation. Do not assume the SEP exists automatically without confirming your plan's coordination policy with OPM.

IRMAA: how your TSP withdrawals can increase your Medicare premiums

This is where TSP planning intersects directly with Medicare costs — and where many federal retirees are surprised.

IRMAA — the Income-Related Monthly Adjustment Amount — is a Medicare surcharge assessed on beneficiaries whose modified adjusted gross income (MAGI) exceeds certain thresholds. The surcharge applies to both Part B and Part D premiums.

For 2026, IRMAA kicks in at:⁴

• Single filers with MAGI above $109,000
• Married filing jointly with MAGI above $218,000

At the first IRMAA tier, Part B premiums jump from $202.90 to $284.10/month — an $81.20/month increase per person. At the highest tier (MAGI above $500,000 single / $750,000 MFJ), Part B premiums reach $689.90/month per person.

IRMAA uses a two-year lookback: your 2026 Medicare premiums are based on your 2024 tax return income. A large TSP withdrawal, a Roth conversion, or a one-time capital gain in 2024 can push you into an IRMAA bracket for 2026 — even if your income in 2025 and 2026 is much lower.

IRMAA and the FERS Supplement gap: a planning window

The FERS Supplement bridges early federal retirement to age 62 — and the period before Social Security starts is often the best window for Roth conversions, because your MAGI is at its lowest.

For a federal employee who retires at 57 with a $48,000 FERS pension, no Social Security yet, and modest TSP installments, annual MAGI might be $60,000–$75,000 — well below the $109,000 IRMAA threshold. That's 8 years of Roth conversion room before Medicare starts, with no IRMAA exposure during those conversions because IRMAA doesn't apply until age 65.

Once Medicare starts at 65, the MAGI from those Roth conversions is behind you. The Roth TSP or Roth IRA balance distributes tax-free and doesn't count toward MAGI at all — reducing IRMAA exposure for the rest of retirement.

This is the central reason the FERS Supplement gap (57–62) and the Medicare window (62–65) are the most valuable Roth conversion years in a federal retiree's lifetime. Converting before Medicare eligibility avoids the 2-year lookback problem entirely for those conversion years.

Three questions to answer before retirement

1. Do I meet the 5-year FEHB rule?

Pull your SF-2809 enrollment history from HR or check your MyFEDS account. If you have any gaps, calculate whether coverage as a family member fills them. Don't assume — verify in writing before your retirement date.

2. What is my projected MAGI at 65?

Run a projection: FERS pension + TSP installments (or RMDs) + Social Security includible amount (up to 85%) + any other income. If you're near $109,000 (single) or $218,000 (MFJ), you have an IRMAA management problem that affects Part B cost for the rest of your life.

Each $1 of MAGI above the IRMAA threshold costs $81.20/month per person in Part B surcharges at the first tier — roughly $974/year per person. Managing income to stay $2,000–$5,000 below the threshold can save thousands annually in Medicare premiums.

3. Which FEHB plan coordinates best with Medicare?

Not all FEHB plans coordinate equally with Medicare. Some plans (like BCBS Standard, BCBS Basic, and several HMOs) are specifically designed with Medicare coordination in mind and waive virtually all cost-sharing when Medicare is primary. Others provide less favorable secondary coverage. The plan you chose as an employee may not be the best plan in retirement once Medicare Part B is primary.

OPM publishes a FEHB plan comparison tool at opm.gov that includes a Medicare coordination filter. Review your options each Open Season — you can switch plans annually.

When dropping FEHB makes sense (and when it doesn't)

Dropping FEHB entirely is rarely the right call. Once you drop it as a retiree, you can only re-enroll during Open Season — and only if you're still eligible as an annuitant. There's no right to re-enroll outside Open Season.

The main scenario where dropping FEHB makes financial sense: if you switch to a Medicare Advantage plan that provides creditable drug coverage and covers all the services your FEHB plan covered, at lower total out-of-pocket cost. Some Medicare Advantage plans in specific markets achieve this — particularly for healthy retirees in good network areas. But the analysis requires comparing the specific MA plan against your specific FEHB option, not a general comparison.

What you'd lose by dropping FEHB: the government's ~72% premium contribution. Even a low-premium FEHB plan has significant hidden government subsidy. Replacing that value in a Medicare Advantage plan is harder than it appears in most markets.

FEHB and the survivor annuity connection

If you elect no survivor annuity for your spouse, your spouse loses FEHB coverage upon your death — unless they were separately enrolled as a federal employee or retiree. FEHB eligibility as an annuitant survivor requires that the annuitant (you) had a survivor benefit in place.

This is the "FEHB trap" in survivor annuity planning: a retiree who elects no survivor annuity to save the 10% reduction may inadvertently cut off their spouse's health coverage in retirement. If your spouse is covered solely through your FEHB enrollment and is not independently enrolled, the no-survivor election eliminates their FEHB access after your death.

If you're considering the no-survivor-annuity election, verify whether your spouse will have independent Medicare + other health coverage, or whether FEHB survivor eligibility is important to your family plan. See our detailed guide on FERS Survivor Annuity Election for the cost structure and break-even math.

What a specialist models here

The FEHB + Medicare + IRMAA decision requires multi-year projections that are specific to your income mix:

• MAGI trajectory from retirement to age 90 — FERS pension, TSP RMDs (age 73 or 75), Social Security (85% includible), and Roth conversion income
• Which years to do Roth conversions and in what amounts to stay under IRMAA thresholds — or consciously cross them when conversion benefit exceeds the surcharge cost
• TSP in-plan Roth conversion vs. rollover to IRA + Roth conversion — which vehicle gives better IRMAA-aware sizing control
• FEHB plan selection post-Medicare: which plan's Medicare coordination rules save the most given your medical utilization pattern
• Impact of IRMAA lookback timing on large withdrawal years (RMD age, one-time capital gain, inheritance)
• Survivor FEHB planning coordinated with survivor annuity election

These variables compound across 20+ years. Getting the IRMAA threshold management right in the first 5 years of retirement — when Roth conversions are cheapest and before Medicare kicks in — is worth far more than the premium savings in any single year.

1. 2026 FEHB premium government contribution: maximum $324.76/month (Self Only), $711.17 (Self Plus One), $778.03 (Self and Family) — 72% of weighted average. Average overall premium increase 10.2% for 2026: OPM — FEHB Premium Rates 2026; OPM — Open Season Highlights 2026.
2. FEHB 5-year retirement eligibility rule — must be enrolled for 5 years immediately before retirement or since first opportunity; family member coverage and TRICARE count toward the 5-year requirement: OPM FastFacts — FEHB and Retirement; OPM — FEHB for Annuitants.
3. 2026 Medicare Part B standard monthly premium $202.90 (up from $185.00 in 2025): CMS — 2026 Medicare Parts A & B Premiums and Deductibles.
4. 2026 IRMAA thresholds: surcharge begins at $109,000 MAGI (single) / $218,000 (MFJ); Tier 1 total Part B premium $284.10/month; top tier $689.90/month at $500,000+ (single) / $750,000+ (MFJ). Two-year lookback applies (2026 IRMAA based on 2024 tax return): SSA POMS HI 01101.020 — IRMAA Sliding Scale Tables; CMS — 2026 Medicare Premiums Fact Sheet.
5. FEHB and Medicare Special Enrollment Period — OPM coordinates an SEP for FEHB enrollees to enroll in Part B after age 65 without late enrollment penalty; documentation required: OPM — Thinking About Retiring (health coverage).
6. SECURE 2.0 § 107 — RMD age 73 for born 1951–1959, age 75 for born 1960+; § 325 — no lifetime RMDs on Roth TSP balances starting 2024: SECURE 2.0 Act of 2022, Pub. L. 117-328.

Values verified as of April 2026. Medicare Part B premiums, IRMAA thresholds, and FEHB government contribution amounts update annually. Confirm current-year values at medicare.gov and opm.gov before finalizing your enrollment decisions.