Medicare vs. Employer Coverage: Which Should You Choose When You Turn 65?

This is one of the most nuanced Medicare questions Ashley Watson fields — and getting it wrong can result in penalties, coverage gaps, or years of unnecessarily high premiums. If you're approaching 65 and still working in San Diego, here's what you need to know.

The Short Answer: It Depends on Your Employer's Size

The most important factor is how many people work for your employer (or your spouse's employer, if that's the source of your coverage).

If Your Employer Has 20 or More Employees

Your employer coverage is considered your primary insurance, and Medicare is secondary. In this case, you generally have the option to delay enrolling in Medicare Part B without facing a late enrollment penalty. You'll have a Special Enrollment Period (SEP) when you retire or lose employer coverage — giving you 8 months to enroll in Part B without penalty.

Most people in this situation choose to enroll in Part A (which is usually free) right away, since it can serve as secondary coverage alongside employer insurance. But they wait on Part B to avoid the monthly premium while they're covered by a strong employer plan.

If Your Employer Has Fewer Than 20 Employees

For small employers, the rules flip: Medicare becomes primary. Your employer plan becomes secondary. If you don't enroll in Medicare Part B when you become eligible, your employer plan may refuse to pay claims it would otherwise cover — and you could face a permanent Part B late enrollment penalty on top of it. Enrolling in Medicare on time is critical in this situation.

How Do You Compare the Costs?

Even if you're allowed to delay Medicare, that doesn't always mean you should. Here's a simple framework for comparing your employer plan against Medicare:

• Compare monthly premiums: What are you paying for employer coverage? How does it compare to Medicare Part B ($185/month in 2025) plus any Advantage or Supplement plan?
• Compare out-of-pocket maximums: Some employer plans have high deductibles. Medicare Advantage plans cap your annual out-of-pocket costs, which can be meaningful if you have ongoing health needs.
• Compare prescription coverage: Is your employer's drug coverage considered "creditable" by Medicare? If yes, you can delay Part D without penalty. If no, you need to enroll in Part D to avoid the late penalty.
• Compare provider networks: Does your employer plan or Medicare Advantage plan cover your existing San Diego doctors?

What About COBRA?

If you retire before 65 and use COBRA to continue your employer coverage until you reach Medicare eligibility, here's a critical warning: COBRA is generally not considered creditable coverage for purposes of avoiding Medicare's late enrollment penalty. When your COBRA ends, you may not have a Special Enrollment Period — you'd need to wait for the next General Enrollment Period (January 1 – March 31) with coverage starting July 1.

Timing your retirement and Medicare enrollment carefully can save you from significant out-of-pocket exposure. This is a situation where talking to Ashley before you retire is genuinely worth the call.

What If You Have a Health Savings Account (HSA)?

If you contribute to an HSA, enrolling in any part of Medicare — even just Part A — makes you ineligible to continue making HSA contributions. If maximizing HSA contributions is important to you in the years before retirement, you'll want to delay Medicare enrollment (and ensure you have an employer plan that allows it). Ashley can walk through the timing with you.

Can I Have Both Medicare and Employer Coverage at the Same Time?

Yes — this is called having "dual coverage" (not to be confused with Medicare + Medi-Cal dual eligibility). When you have both, one plan pays first (primary) and the other pays second (secondary). Coordination of benefits between the two can significantly reduce your out-of-pocket costs. Whether Medicare is primary or secondary depends on your employer's size, as described above.

The Bottom Line

The right answer for you depends on your employer's size, your premium costs, your health needs, your medications, and your retirement timeline. There's no one-size-fits-all rule — but there are specific questions you can ask and specific rules you need to know to make the right decision.

Ashley Watson specializes in helping San Diego County residents navigate exactly this kind of transition. A single free consultation can help you avoid a permanent penalty or an unnecessary premium — and give you a clear plan for the road ahead.

Talk to a Local Expert Before You Decide

Don't guess on this one. Schedule a free consultation with Ashley Watson or call (619) 947-2325. She'll look at your specific situation — employer size, plan details, retirement timeline, and health needs — and give you a clear, honest recommendation.