A lot of folks who turn 65 are still working. They have a group health plan through the employer, they're comfortable with it, and they figure they'll deal with Medicare when they actually retire.
Sometimes that's the right call. Sometimes it costs them money they didn't need to spend.
Being comfortable with your group plan doesn't mean you're done looking.
You've paid into Medicare your entire working life. You owe it to yourself to take 30 minutes and compare what you have at work to what Medicare actually offers. A lot of folks find out they're paying more than the current Part B rate, and carrying a deductible at work, when many Medicare plans cost only the Part B premium with no medical deductible.
That's what we often find. It isn't a promise of what every reader will find. The right answer depends on your specific group plan, your prescriptions, your doctors, and your income.This article covers the rules that govern Medicare and employer coverage, the deadline traps that can cost you for life, and what to actually compare if you're deciding whether to stay or switch.
The 60-second framing
If you're 65 and still working, you have three big questions to answer: (1) Do you have to enroll in Medicare now, or can you delay it? (2) If you can delay, should you? (3) What changes when you finally do leave employer coverage?
The rules depend on how big your employer is, whether your coverage is "creditable" for Medicare's purposes, and whether you contribute to an HSA. Get these wrong and you can hit penalties that last for life. Get them right and you have more flexibility than most folks realize.
"I'm happy with my group plan — should I even look?"
This is the question I get most often, so let me answer it honestly.
You don't have to switch. Plenty of folks past 65 stay on their group plan all the way to retirement and never regret it. But "I'm comfortable with what I have" isn't the same thing as "what I have is the best fit for me." Comfort is what you know. Fit is what works on paper.
Two diagnostic questions tell you whether a comparison is worth your time:
Is your monthly group premium higher than $202.90?
That's the standard 2026 Part B premium. If you're paying more out of your paycheck for the employer plan than Medicare's Part B would cost you, that's a flag — not because Medicare is automatically better, but because the price gap is worth a look.
Does your group plan have a medical deductible?
Many do. Most Medicare plans we work with don't carry a medical deductible at all beyond Part B's $283 — and on Original Medicare with a Supplement, the Supplement usually picks that up. For folks who go to the doctor regularly, the absence of a deductible can change the math meaningfully.
If either answer is "yes," a 30-minute comparison is worth it. We don't charge for it. If the group plan is actually the better fit, that's what we'll tell you.
The framing I want you to leave with: you've paid into this system for decades. The 30-minute comparison costs you nothing and tells you whether you've been missing something. That's worth doing.
The 20-employee threshold
The biggest legal piece of working-past-65 Medicare planning is the size of your employer.
Employer with 20+ employees
- Your group plan is the primary payer.
- Medicare is secondary (if you enroll).
- You can usually delay Part B without penalty.
- You'll get an 8-month Special Enrollment Period for Part B when you leave the coverage.
- You're considered to have "current creditable coverage."
Employer with fewer than 20 employees
- Medicare is the primary payer.
- Your group plan pays second.
- You should enroll in Part B at 65.
- Skipping Part B can leave a huge coverage gap.
- Delaying can trigger lifetime penalties.
If you're not sure whether your employer is over or under 20, ask HR directly. The threshold is the average number of employees over the prior calendar year. Some larger holding companies count corporate-wide; some count by division. Don't guess.
What is "creditable coverage"?
This is the part that trips people up most.
For Part B late-enrollment penalty purposes, "creditable coverage" means coverage through an actively-employed person (you or your spouse) at an employer with 20+ employees. Retiree coverage, COBRA, VA benefits, and individual marketplace plans do not count.
For Part D late-enrollment penalty purposes, "creditable drug coverage" means drug coverage that's expected to pay at least as much as Medicare's standard Part D plan would. Most active-employee group plans qualify. Many retiree plans do not. Your group plan administrator has to tell you every year whether your plan is creditable — that notice usually comes in the fall.
A few facts that surprise people:
- COBRA is not creditable coverage for Part B. If you leave employment and go onto COBRA, COBRA does not protect you from Part B late penalties. You need to enroll in Part B within 8 months of losing the active employer coverage, even if you're still on COBRA.
- Retiree-only coverage is not creditable for Part B. Same rule — if you're past 65 and on retiree health coverage from a former employer, you should be enrolled in Part B.
- Tricare and FEHB have their own rules. Tricare-for-Life requires Part B enrollment. FEHB doesn't require Part B but coordinates differently with Medicare; ask your HR.
We see the COBRA mistake the most. People leave their job, go onto COBRA, assume they're covered, and don't enroll in Part B for 12–18 months. That's a permanent penalty on top of the gap-coverage exposure.
The HSA contribution trap
This one is technical but important.
If you contribute to a Health Savings Account through your employer, and you (or your employer on your behalf) want to keep contributing past 65, you cannot enroll in any part of Medicare — including premium-free Part A.
Most folks who delay Medicare enrollment to keep contributing to an HSA think they can sign up later and the contributions are clean. There's a catch: when you eventually enroll in Part A (which is automatic when you start Social Security retirement benefits), Medicare back-dates your Part A eligibility up to 6 months. If you contributed to an HSA during that retroactive window, those contributions become disallowed and can trigger tax penalties.
The cleanest play if you want to maximize HSA contributions: stop HSA contributions 6 months before you plan to enroll in Medicare (or before you plan to start Social Security). We'll walk you through the timing if HSA preservation matters to your retirement plan.
When you leave employer coverage (the SEP)
When your active employer coverage ends — because you retire, switch jobs, lose hours, or your spouse retires (if you were on their plan) — you have an 8-month Special Enrollment Period to sign up for Part B without penalty.
The clock starts the month after your employment ends or the month after your employer coverage ends, whichever is earlier. COBRA does not extend it.
There's a separate 63-day SEP for Part D enrollment when you lose creditable drug coverage. Don't miss it; the Part D penalty is permanent.
The cleanest path: enroll in Part B effective the first of the month your employer coverage actually ends. Apply about a month in advance through Social Security. If you wait, you can leave yourself uninsured for a few weeks.
Spouse coverage considerations
Many folks work past 65 in part because their spouse is on their group health plan and isn't yet 65 themselves. The rules:
- Spouse on your employer plan, both under 65: nothing changes.
- You turn 65, spouse stays on your active-employee plan: your spouse keeps the employer coverage. You decide whether to take Part B or delay.
- You retire before spouse turns 65: your spouse loses employer coverage and has to find individual marketplace coverage or coverage through their own employer. This is one of the most common reasons folks delay full retirement.
- Spouse turns 65 first, you're still working: your spouse can take Medicare or stay on your active-employee plan. Same comparison applies.
Real St. Louis scenarios
We see these patterns regularly in our office:
- Boeing retirement. Many Boeing retirees go onto the retiree health benefit, which is not creditable for Part B — they need to enroll in Part B on time. The retiree drug benefit varies in creditability year to year; check the annual notice.
- BJC and Mercy retirement. Hospital-system retiree benefits vary. Some are creditable for Part D; many are not. Confirm with HR.
- Anheuser-Busch and other large-employer retirement. Many large St. Louis employers have retiree coverage that coordinates with Medicare and assumes you'll enroll in Part B. Confirm what your post-65 contribution obligation looks like.
- Small St. Louis professional practices. Law firms, accounting firms, family-owned businesses under 20 employees — Medicare is primary. Enroll in Part B at 65 or accept a coverage gap.
We've sat in the kitchen-table conversation for plenty of these. The HR materials don't always make the Medicare interplay clear. We do.
Take the 30 minutes
If you're 65 and still working, do the comparison. Even if you stay on your group plan, you'll know what you have versus what Medicare offers — and you'll catch the deadline traps before they cost you.
I've been helping people with Medicare in St. Louis since 2013. The working-past-65 conversation is the one we wish more folks had earlier, because the penalties for getting it wrong don't go away.
No fee, no pressure, no sales pitch — that's the rule of the house. We answer every call.
