FEHB in Retirement: Should You Keep It or Switch to Medicare?

For most federal employees, health insurance has always been straightforward — you pick an FEHB plan, your agency pays most of the premium, and you’re covered. But when you retire, that simplicity ends. Suddenly you’re making decisions about Medicare enrollment windows, coordination of benefits, and whether your monthly costs go up or down depending on which path you choose.

This is one of the most consequential and misunderstood decisions in federal retirement. Here’s what actually matters.

The First Question: The 5-Year Rule

Before anything else: to carry FEHB into retirement, you must have been continuously enrolled in FEHB — or covered as a family member — for the five years immediately before your retirement date.

This is non-negotiable. If you haven’t met the five-year requirement, you cannot carry FEHB coverage into retirement at all, which changes the entire healthcare calculation. Verify your enrollment history with your HR Benefits Officer before assuming you qualify.

Understanding Your Options at 65

When you turn 65, Medicare becomes available. You have three paths:

1. Keep FEHB only. You can stay enrolled in FEHB and decline Medicare Part B entirely. You’ll pay no Part B premium, but FEHB acts as your sole coverage.
2. FEHB + Medicare Part A only. Medicare Part A (hospital coverage) is free for most people who’ve paid Medicare taxes. Adding it costs nothing and FEHB remains your primary coverage.
3. FEHB + Medicare Parts A and B. This is the most comprehensive option. Medicare becomes primary, FEHB becomes secondary — and together they can dramatically reduce out-of-pocket costs. The trade-off: Medicare Part B carries a monthly premium (in 2026, the standard amount is $185/month, though higher earners pay more via IRMAA surcharges).

How FEHB and Medicare Work Together

When you have both FEHB and Medicare Part B, Medicare pays first (primary) and FEHB pays second (secondary). The result: many costs that Medicare doesn’t fully cover — like copays, coinsurance, and deductibles — get picked up by FEHB. In practice, many federal retirees with both coverages pay very little out of pocket for most healthcare services.

The Key Trade-Off: Premium vs. Out-of-Pocket

Adding Medicare Part B means paying an additional monthly premium — roughly $185/month in 2026 for most enrollees, or $2,220/year. Whether that’s worth it depends on your expected healthcare usage.

For healthy retirees with low healthcare utilization, paying $2,220/year for Part B coverage they rarely use may not pencil out. For retirees with chronic conditions, frequent specialist visits, or hospitalizations, the coordination benefits can far outweigh the premium cost.

There’s no universal right answer — it’s a math problem specific to your health situation and your specific FEHB plan’s cost-sharing structure.

The Medicare Part B Late Enrollment Penalty — Don’t Miss This

If you delay enrolling in Medicare Part B past your Initial Enrollment Period (the seven months around your 65th birthday) and later decide you want it, you’ll pay a permanent late enrollment penalty — 10% added to your premium for every 12-month period you were eligible but didn’t enroll.

The exception: if you’re still actively employed and covered by an employer plan (FEHB counts), you have a Special Enrollment Period when you retire that lets you enroll in Part B without penalty. This window matters — missing it is a costly and permanent mistake.

Three Questions to Answer Before You Decide

1. Do I meet the 5-year FEHB enrollment requirement? Verify with HR before assuming the answer is yes.
2. What is my expected healthcare usage in retirement? High utilization favors adding Part B. Low utilization may not justify the premium.
3. What does my specific FEHB plan charge for coordination with Medicare? Some FEHB plans actually waive premiums entirely for retirees who enroll in Medicare Part B — a significant financial benefit worth checking.

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Sources: Federal News Network, March 2026; OPM Healthcare; Medicare.gov. This article is for educational purposes only and does not constitute financial, legal, or retirement advice.