At 65, the Medicare mail starts pouring in — "Enroll now!" "Don't miss your deadline!" But if you're still working and happy with your employer health plan, signing up at the wrong time, or for the wrong parts of Medicare, can cost you money for the rest of your life.

Here's the good news: if you have solid employer coverage, you often can wait — but only if you understand the rules. Get one of them wrong (especially the HSA rule or the COBRA rule) and it gets expensive fast. I'm Ben Mauldin, a licensed agent in Lexington, and here's the plain-English version for South Carolinians working past 65.

The one question that decides everything: how big is your employer?

Before anything else, find out how many employees your company has. This single fact changes the entire strategy:

• 20 or more employees: Your employer group plan stays primary, and you can generally delay Medicare Part B (and often Part A) without any penalty while you keep working. Many people in this situation are better off staying on the employer plan for now.
• Fewer than 20 employees: Medicare usually becomes the primary payer at 65, and the employer plan pays second. In that case you typically should enroll in Part B at 65, because if you don't, you could be stuck paying for care Medicare would have covered.

So step one isn't "should I take Medicare?" It's "how many people work at my company?" Ask HR, in writing.

Should you still take Part A? Usually yes — unless you have an HSA

Medicare Part A (hospital coverage) is premium-free for most people, so the instinct is to just take it at 65 even while working. For many, that's fine — it can act as secondary coverage at no cost.

But there's a major exception: if you contribute to a Health Savings Account (HSA). This is the trap that catches high-earning South Carolina professionals every year.

The HSA trap (the one nobody warns you about)

Here's the rule: once you're enrolled in any part of Medicare — including free Part A — you can no longer contribute to an HSA.

And it gets trickier. When you enroll in premium-free Part A after 65, Medicare backdates your coverage up to six months (but never before your 65th birthday). So any HSA contributions you made during that retroactive window become excess contributions, subject to a 6% excise tax if not corrected.

What to do: if you want to keep contributing to your HSA while working past 65, you must delay Part A (and not claim Social Security yet, because claiming Social Security automatically enrolls you in Part A). And when you're ready to enroll in Medicare or start Social Security, stop your HSA contributions at least six months beforehand so the backdating doesn't overlap. This one detail alone is worth a conversation before you file for anything.

When you stop working: your 8-month window

When you (or your working spouse) eventually retire or lose the employer coverage, a clock starts. You get a Special Enrollment Period (SEP) — 8 months — to enroll in Medicare Part A and Part B without a late penalty.

To use it smoothly, your employer completes CMS Form L564, which proves you had active group coverage since 65. Don't wait until the last minute — enroll so your Medicare starts the day your employer coverage ends, with no gap.

Miss that window and you face the Part B late penalty: 10% added to your premium for every 12 months you could have had it but didn't — for life. That's the "wrong call costs you forever" part.

The COBRA trap (this one surprises almost everyone)

Here's the mistake that costs people the most, so read this twice: COBRA does not count as active employer coverage for Medicare.

If you delay Part B while working, then leave your job and go on COBRA, you do not get a new Special Enrollment Period when COBRA ends. Your 8-month window starts when your active employment ended — not when COBRA runs out. People assume COBRA keeps their Medicare options open; it doesn't. If you're 65+ and leaving a job, enroll in Medicare based on your active-employment end date, and treat COBRA as a supplement at best — not a reason to delay Part B.

Don't forget your prescription (Part D) coverage

One more box to check: is your employer's drug coverage "creditable" (at least as good as Medicare Part D)? Most large employer plans are, which means you can keep it and skip Part D without a penalty while you're working. Your plan should send you a creditable-coverage notice each year — keep it. If your drug coverage is not creditable, that changes the math, and you'll want to look at Part D.

Quick decision guide

• Employer has 20+ employees, good coverage, no HSA: You can usually take free Part A and delay Part B. Revisit when you retire.
• Employer has 20+ employees and you want to keep funding an HSA: Delay all of Medicare (including Part A), don't claim Social Security yet, and stop HSA contributions 6 months before you eventually enroll.
• Employer has fewer than 20 employees: Strongly consider enrolling in Part B at 65 — Medicare is likely your primary coverage.
• Leaving your job at 65+: Enroll in Part B within 8 months of your active employment ending. Don't let COBRA fool you.

What to Do Before you make any Medicare move while working: (1) confirm your employer's size, (2) check whether your drug coverage is creditable, (3) if you have an HSA, plan the 6-month stop, and (4) when you retire, use your 8-month SEP with the CMS-L564 form. I'll walk through your specific situation with you at no cost so you don't trip a penalty or an HSA tax.

If you want the standard retirement-timeline version, our Turning 65 in South Carolina guide covers the deadlines for people who are retiring, and when you're ready to pick coverage, Medicare Advantage vs. Medigap in South Carolina lays out the choice. Prefer to talk to someone? Here's local Medicare help in the Columbia area.

Working Past 65? Let's Get Your Medicare Timing Right — for Free.

No-cost, no-pressure review. I'll help you decide what to take now, what to delay, how to protect your HSA, and how to enroll cleanly when you retire — no penalties, no gaps.

📞 Call or Text Ben: 803-920-8827 🌐 MauldinInsuranceGroup.com 📍 100 Old Cherokee Rd STE F #167, Lexington, SC · Serving all of South Carolina

This article is general information, not enrollment or tax advice. Confirm your situation with Social Security (ssa.gov), Medicare (1-800-MEDICARE), your benefits department, and your tax professional.

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Frequently Asked Questions

Do I have to enroll in Medicare at 65 if I'm still working in South Carolina? Not always. If your employer has 20 or more employees and you have good coverage, you can usually delay Part B without penalty and stay on the employer plan. If your employer has fewer than 20 employees, Medicare is often primary, so you generally should enroll in Part B at 65.

Can I delay Medicare Part B while I'm still working? Yes, if your employer has 20 or more employees and provides active group coverage. You'll get an 8-month Special Enrollment Period to enroll in Part B without penalty after your employment or coverage ends. Your employer completes Form CMS-L564 to document your active coverage.

Can I contribute to my HSA if I'm on Medicare? No. Once you enroll in any part of Medicare — including premium-free Part A — you can no longer contribute to an HSA. Because Part A can backdate up to six months when you enroll after 65, you should stop HSA contributions at least six months before enrolling in Medicare or claiming Social Security.

Does COBRA count as coverage that lets me delay Medicare? No. COBRA is not considered active employer coverage for Medicare. If you're 65 or older, your Special Enrollment Period starts when your active employment ends, not when COBRA ends — so enroll in Part B based on your active-employment end date to avoid a lifelong late penalty.

What is the penalty for not enrolling in Part B on time? If you don't enroll when you're supposed to, Medicare adds 10% to your Part B premium for every 12 months you could have had it but didn't — and that penalty generally lasts for the rest of your life.

Do I need Medicare Part D if I have employer drug coverage? Usually not, if your employer's drug coverage is "creditable" (at least as good as Part D). Most large employer plans are, which lets you skip Part D without penalty while working. Keep the creditable-coverage notice your plan sends each year.