Key Takeaways

• Having other health coverage doesn’t always exempt you from enrolling in Medicare when you’re eligible—especially if you’re turning 65 in 2025 or have already reached that age.

• Missing your Medicare enrollment window could result in lifelong penalties and a delay in coverage, even if you already have insurance through an employer, retiree plan, or spouse.

Why Having Other Coverage Doesn’t Automatically Exempt You

It might seem logical to delay Medicare enrollment if you already have health coverage. However, the Medicare system has very specific coordination rules that apply depending on the type of insurance you have, your age, and your employment status. Not understanding these distinctions could leave you facing late enrollment penalties or unexpected gaps in coverage.

Here’s what matters most: not all coverage types allow you to delay Medicare without consequences. And even when they do, you often need to take proactive steps to ensure that you meet Medicare’s criteria for a valid delay.

Understand the Role of Employer Coverage

If you’re still working in 2025 and have group health insurance through your job or your spouse’s job, your employer size plays a critical role.

Large Employer Group Health Plans (20+ Employees)

• If your coverage is from an employer with 20 or more employees, you can usually delay Medicare Part B without penalty.

• Medicare is secondary in this scenario, meaning your employer plan pays first.

• When you retire or lose this coverage, you’ll be eligible for a Special Enrollment Period (SEP) to sign up for Medicare Part B without penalty, lasting 8 months from the loss of coverage.

Small Employer Group Health Plans (Fewer than 20 Employees)

• Medicare becomes the primary payer, even if you’re still working.

• Your employer plan will only pay after Medicare pays its share.

• If you don’t enroll in Medicare when first eligible, you may not be fully covered—and worse, you could face late enrollment penalties.

Retiree Health Plans Don’t Replace Medicare

You might have retiree health benefits from a former employer, union, or government job. In most cases, these plans are designed to work with Medicare, not instead of it.

• Retiree plans often require you to enroll in both Medicare Part A and Part B once you’re eligible.

• If you skip Part B, the retiree plan may reduce benefits or deny claims altogether.

• These plans typically become secondary to Medicare.

In 2025, retiree coverage that doesn’t coordinate with Medicare is rare. Assuming your plan offers full coverage without Medicare can be a costly mistake.

COBRA and Medicare: A Fragile Combination

COBRA coverage allows you to extend employer-sponsored coverage temporarily after job loss. But it has limits when you become Medicare-eligible.

• If you’re already enrolled in COBRA when you become eligible for Medicare, you must sign up for Medicare Part B.

• If you delay enrolling in Part B beyond your Initial Enrollment Period (IEP), you will not qualify for a Special Enrollment Period when COBRA ends.

• Medicare pays primary once you’re eligible, and COBRA pays secondary—if you have both.

In short, COBRA is not a substitute for Medicare and should not be treated as such.

Tricare for Life Requires Medicare Enrollment

For military retirees who qualify for Tricare for Life (TFL), enrollment in Medicare Part A and Part B is mandatory.

• TFL only activates after you enroll in both parts.

• If you skip Part B, your TFL benefits will be suspended.

Since 2025 changes have tightened enforcement around this requirement, it’s essential to plan ahead and enroll in time.

FEHB: Don’t Assume It’s Enough on Its Own

The Federal Employees Health Benefits (FEHB) Program covers many government retirees. While FEHB is comprehensive, it’s not a replacement for Medicare.

• Once you retire and become eligible for Medicare, most FEHB plans become secondary.

• Some FEHB plans reduce out-of-pocket costs if you’re enrolled in Medicare Part B.

• Failure to enroll in Medicare may increase your costs or reduce your FEHB coverage benefits.

It’s also important to note that as of 2025, Postal retirees must enroll in the new Postal Service Health Benefits (PSHB) Program, which requires Medicare Part B enrollment unless exempt.

Spouse Coverage Might Not Protect You

Being covered under a spouse’s employer plan does not always let you delay Medicare.

• If your spouse’s employer has 20 or more employees, you may defer Medicare Part B without penalty.

• If the employer has fewer than 20 employees, Medicare must be your primary coverage, even if your spouse is still working.

• If you delay Part B under these conditions, penalties may apply, and your claims may go unpaid.

Don’t assume your spouse’s coverage will give you a free pass. Always confirm the employer size and how the plan coordinates with Medicare.

Initial Enrollment Period Still Applies

When you first become eligible for Medicare—typically at age 65—you enter a 7-month Initial Enrollment Period (IEP).

• It begins 3 months before your 65th birthday, includes your birthday month, and ends 3 months after.

• During this window, you should enroll in Medicare Parts A and B unless you have qualifying employer coverage.

If you miss this window and don’t qualify for a Special Enrollment Period later, you may be locked out until the General Enrollment Period (January 1 to March 31), with coverage starting in July and penalties permanently added to your premiums.

Late Enrollment Penalties Can Be Lifelong

If you don’t sign up for Medicare when required, you could face penalties:

• Part B: A 10% premium increase for each 12-month period you were eligible but didn’t enroll. This increase lasts as long as you have Medicare.

• Part D: A 1% penalty for every month you delay enrollment without other creditable prescription coverage.

These penalties can add up over time, especially if you delayed coverage thinking your current insurance was sufficient.

Medicare as Secondary Insurance Has Limits

Even when Medicare is not your primary insurance, failing to enroll can still cause issues:

• Your current insurer may reduce what they pay once you become eligible for Medicare.

• Claims may be delayed or denied while payers determine which is primary.

• Some services might not be covered at all without Medicare enrollment.

If Medicare is meant to be the primary payer but you aren’t enrolled, you could be liable for the full cost of care.

What to Do Before Turning 65 in 2025

Planning ahead is essential. If you’re approaching age 65 this year, here are some actions to take:

• Review your current coverage: Is it from a large employer? Is it retiree, COBRA, or individual coverage?

• Contact your HR department or plan administrator: Confirm whether Medicare should be primary.

• Check plan documentation: Look for language requiring Medicare enrollment at age 65.

• Talk with a licensed agent listed on this website: They can walk you through the coordination rules and timelines.

A few proactive conversations now can save you from expensive missteps later.

Final Thoughts on Overlapping Coverage and Medicare Requirements

It’s easy to overlook Medicare enrollment if you’re already covered, but in most cases, it’s not optional. In 2025, stricter enforcement of Medicare coordination rules makes timely enrollment more critical than ever. Your existing coverage may not protect you from penalties or gaps in benefits unless it fits Medicare’s definition of valid group health coverage.

Be sure to assess your insurance type, confirm its coordination status, and plan your Medicare enrollment accordingly. To avoid missteps, get in touch with a licensed agent listed on this website who can help ensure your transition is smooth and penalty-free.