Working Past 65 with Employer Coverage: Do You Need Medicare?

The Short Answer

Why it matters: Employer size determines which insurance pays first (primary) and which pays second (secondary). Making the wrong choice can leave you underinsured or facing permanent financial penalties.

The 20-Employee Rule Explained

Medicare has a coordination-of-benefits rule that determines which insurance pays first.

Large Employer (20+ Employees)

When you work for an employer with 20 or more employees:

• Employer insurance is primary — It pays first
• Medicare is secondary — It pays what's left (if you have it)
• You CAN delay Part B — No penalty when you eventually enroll
• Part A is often worth enrolling in — It's free for most and provides backup hospital coverage

What this means for you: Your employer coverage works like it always has. Medicare is optional while you're working and covered.

Small Employer (Under 20 Employees)

When you work for an employer with fewer than 20 employees:

• Medicare is primary — It pays first
• Employer insurance is secondary — It only pays what Medicare doesn't
• You MUST enroll in Part A and Part B — Delaying Part B triggers late penalties
• Without Medicare, you're underinsured — Employer coverage alone won't pay claims properly

How to Determine Employer Size

Count all employees, not just at your location:

• Include full-time employees
• Include part-time employees
• Include employees at all company locations
• Count based on 20+ weeks in the current or preceding year

Ask your HR department: “Does our company have 20 or more employees for Medicare coordination purposes?”

Get it in writing: If you're close to the threshold, documentation protects you.

Your Options at 65 (and Beyond)

These rules apply whether you're 65, 67, 70, or any age — the employer size rule doesn't change based on how long you've been Medicare-eligible.

Part A vs. Part B: The Decision

Part A (Hospital Insurance)

• Cost: Free for most people (if you or your spouse worked 40+ quarters)
• What it covers: Inpatient hospital stays, skilled nursing facility care, hospice, some home health
• Recommendation: Usually enroll even if you have employer coverage — it's free backup coverage

Exception: If you have a Health Savings Account (HSA), see the HSA section below.

Part B (Medical Insurance)

• Cost: $202.90/month in 2026 for most people
• What it covers: Doctor visits, outpatient care, preventive services, medical equipment
• Recommendation:
  • 20+ employees: Can delay without penalty while you have creditable employer coverage
  • Under 20 employees: Enroll when first eligible to avoid penalties and coverage gaps

The HSA Complication

If you have a High Deductible Health Plan (HDHP) with a Health Savings Account (HSA), Medicare enrollment changes your options:

The rule: You cannot contribute to an HSA once you're enrolled in any part of Medicare — including free Part A.

Why this matters:

• Part A enrollment can be retroactive up to 6 months
• If you claim Social Security at 65+, you may be automatically enrolled in Part A
• HSA contributions made after Medicare enrollment can trigger tax penalties

Strategy for HSA Holders

1. Stop HSA contributions 6 months before enrolling in Part A — This avoids the retroactive enrollment overlap
2. Delay Part A if maximizing HSA contributions is a priority — But weigh this against free hospital coverage
3. Keep your HSA funds — You can still use existing HSA money for qualified medical expenses; you just can't add new contributions
4. Enroll in Part B when employment ends — Via your 8-month Special Enrollment Period

2026 Part B Costs and Late Enrollment Penalties

If You Enroll on Time

If You Delay When You Shouldn't Have

The Part B late enrollment penalty is 10% added to your premium for each 12-month period you should have had Part B but didn't. This penalty is permanent — you pay it for as long as you have Part B.

Part D (Drug Coverage) Penalty

If you go more than 63 days without creditable drug coverage, you'll also face a permanent Part D late enrollment penalty — 1% of the national base premium for each month without coverage. See creditable coverage and Medicare for the rules.

What Happens When You Stop Working

When your employment or employer coverage ends, you have a window to enroll in Medicare without penalty.

Special Enrollment Period (SEP)

• Length: 8 months to enroll in Part B without penalty
• When it starts: The month your employment OR coverage ends (whichever is first)
• Best practice: Apply early — don't wait until the last month to avoid coverage gaps

Timeline Example

Documents You'll Need

• CMS-L564: Request for Employment Information (your employer completes this)
• CMS-40B: Application for Enrollment in Medicare Part B
• Proof of employment dates and coverage

COBRA Coverage Warning

Retiree Coverage Considerations

Retiree coverage from a former employer is also different from active employment coverage:

• Retiree insurance typically expects you to have Medicare
• Many retiree plans are designed as secondary to Medicare
• Not enrolling in Medicare while on retiree coverage can leave you underinsured

Ask your former employer: “Does the retiree plan require Medicare enrollment?”

What About Your Spouse's Employer Coverage?

The same rules apply if you're covered through your spouse's employer:

The test: Is the coverage based on current employment at a company with 20+ employees? If yes, you can delay. If no, you should enroll.

Frequently Asked Questions

Not Sure What to Do? Compare Your Employer Plan Against Medicare

The 20-employee rule decides whether you can delay Medicare — but it doesn't tell you whether you should. The right answer depends on the specifics of your employer plan: premiums, deductibles, prescription coverage, and how it would coordinate with Medicare.

Our Employer Plan Comparison tool lines your workplace coverage up against the Medicare options available in your area, side by side. Search your employer plan, answer a few quick questions, and see which path actually saves you money for your situation.

Compare My Employer Plan to Medicare →

Prefer to talk it through? Call 866-764-3312 and a licensed Medicare advisor will walk you through your specific employer plan and your Medicare options. We'll tell you whether to keep employer coverage or switch — even though we only get paid if you choose Medicare.