Do I Need Medicare If I'm Still Working?

Updated for 2026. If you’re approaching 65 but still have employer health insurance, you’re facing one of the most confusing Medicare decisions. The rules depend on your employer’s size, your spouse’s coverage, and your specific situation. Make the wrong choice and you could face permanent penalties. Here’s everything you need to know.

The Critical Rule: Your Employer’s Size Determines Everything

Whether you need to enroll in Medicare while still working depends primarily on one factor: how many employees your company has. This single detail determines which insurance is “primary” (pays first) and which is “secondary” (pays second). Getting this wrong can lead to denied claims and unexpected medical bills.

In short: 20+ employees means your employer plan pays first; under 20 employees means Medicare pays first; and delaying Part B without qualifying coverage costs an 8% penalty per year delayed.

Scenario 1: You Work for a Large Employer (20+ Employees)

If your employer has 20 or more employees, your employer’s group health plan is the primary payer. This means:

• Your employer coverage pays first for medical claims
• You can safely delay Medicare Part B without penalty
• You should still enroll in Part A (it’s free and can serve as secondary coverage)
• You do NOT need Part D if your employer drug plan is “creditable coverage” (they must notify you annually)
• When you retire or lose employer coverage, you get a Special Enrollment Period (SEP), 8 months to sign up for Part B without penalty

Should You Still Enroll in Part A?

In most cases, yes. Part A is premium-free and serves as a backup to your employer coverage. If you’re hospitalized, your employer plan pays first, then Part A picks up remaining costs. There’s essentially no downside.

Exception: If you have a Health Savings Account (HSA), do NOT enroll in Part A. Once you have any Medicare coverage (including Part A), you can no longer contribute to an HSA. If you want to keep contributing to your HSA, delay all parts of Medicare.

The HSA and Medicare Trap

This catches many people off guard. Here are the rules:

• You cannot contribute to an HSA once enrolled in any part of Medicare
• Social Security will automatically enroll you in Part A when you start Social Security benefits
• If you’re 65+ and want to keep your HSA, do NOT file for Social Security yet
• Part A enrollment is retroactive 6 months, so if you sign up for Part A in June, it’s effective from January. You’d owe back any HSA contributions made during those months.
• Consider stopping HSA contributions 6 months before you plan to enroll in Part A

Scenario 2: You Work for a Small Employer (Under 20 Employees)

If your employer has fewer than 20 employees, the rules flip completely. Medicare becomes your primary coverage at age 65, and your employer plan becomes secondary. This means:

• You MUST enroll in Medicare Part A and Part B when first eligible
• If you don’t enroll, your employer plan may not cover claims properly, they’ll assume Medicare is paying first
• You could end up with claims denied by BOTH insurers
• If you delay Part B, you’ll face permanent late enrollment penalties when you do enroll

Warning: If you work for a small employer and don’t sign up for Medicare at 65, your employer plan will treat Medicare as your primary insurer, even though you haven’t enrolled. Claims will be paid at the secondary rate, leaving you responsible for the difference. You could face thousands in unexpected bills.

Scenario 3: Your Spouse Has Employer Coverage

The same 20-employee rule applies if you’re covered under your spouse’s employer plan:

• Spouse’s employer has 20+ employees: You can delay Part B without penalty while covered under their plan
• Spouse’s employer has under 20 employees: You must enroll in Medicare at 65, regardless of spousal coverage
• When your spouse retires or you lose coverage, you get an 8-month SEP to enroll in Part B

Scenario 4: COBRA Coverage

This is a common and costly mistake. COBRA does NOT count as current employer coverage. If you’re on COBRA when you turn 65:

• You must enroll in Medicare Parts A and B during your Initial Enrollment Period
• COBRA becomes secondary to Medicare once you’re enrolled
• If you delay Medicare enrollment because you have COBRA, you will face late enrollment penalties
• Most people should drop COBRA once they have Medicare plus a supplement or Advantage plan

Scenario 5: Federal Employee Health Benefits (FEHB)

If you’re a federal retiree with FEHB:

• You can keep FEHB alongside Medicare
• Enrolling in Part B is optional but recommended, your FEHB plan often becomes much more generous with Medicare as the primary payer
• Many FEHB plans waive copays and deductibles when Medicare pays first
• You won’t face a late enrollment penalty if you have FEHB, but enrolling in Part B at 65 typically gives you the best overall coverage and lowest out-of-pocket costs

Understanding Part B Late Enrollment Penalties

If you should have enrolled in Part B but didn’t, you’ll face a permanent penalty of 10% for every full 12-month period you were eligible but not enrolled and didn’t have qualifying coverage.

Example Penalty Calculation

Say you turned 65 in 2023, worked for a small employer (under 20), didn’t sign up for Part B, and finally enrolled in 2026:

• 3 years delayed = 30% permanent penalty on Part B premiums
• 2026 standard Part B: $202.90/month
• Your Part B with penalty: $240.50/month, for life
• You can only enroll during the General Enrollment Period (January 1 - March 31), with coverage starting July 1

Use our Part B Penalty Calculator to see exactly what you’d pay.

Step-by-Step: What to Do When You’re Turning 65 and Still Working

1. Find out your employer size: Ask HR how many employees the company has. The 20-employee threshold is what matters.
2. Check your drug coverage: Ask if your employer drug plan is “creditable” (at least as good as Medicare Part D). They must send you a notice annually.
3. Consider your HSA: If you have an HSA and want to keep contributing, plan carefully around Part A enrollment.
4. Talk to your HR/benefits department: Get their guidance on how your employer plan coordinates with Medicare.
5. Consult a Medicare specialist: An independent agent can review your specific situation and help you avoid costly mistakes. This consultation is free.
6. Get enrollment timing right: Mark your Initial Enrollment Period on your calendar and don’t miss deadlines.

Frequently Asked Questions

Can my employer force me to enroll in Medicare?

No. Your employer cannot force you to sign up for Medicare. However, if you work for a small employer (under 20), failing to enroll means your employer plan becomes secondary and may not cover claims properly. It’s in your best interest to enroll on time.

What if my employer has both full-time and part-time employees?

CMS counts all employees, full-time and part-time, when determining the 20-employee threshold. If the company has 20+ total employees at any point during the year, the large employer rules apply.

I’m self-employed. Do I need Medicare at 65?

Yes. Self-employment does not provide a Special Enrollment Period. You should enroll in Medicare during your Initial Enrollment Period around your 65th birthday. If you have a Marketplace (ACA) plan, you must switch to Medicare, you cannot receive ACA subsidies once eligible for Medicare.

What if I retire mid-year?

When you retire and lose employer coverage, you have an 8-month Special Enrollment Period to sign up for Part B without penalty. Don’t wait until the next General Enrollment Period, sign up as soon as you lose coverage. Contact Social Security to initiate enrollment.

My employer coverage is better than Medicare. Should I still enroll?

If your employer has 20+ employees, you can keep employer coverage as primary and delay Part B. But always enroll in Part A (unless you have an HSA) since it’s free. When you eventually retire, compare your options: Original Medicare + Medigap often provides better nationwide coverage than employer plans.