Can I Delay Medicare Part B? When It's Safe and When It Costs You

The Short Answer

Yes — but only if you have health coverage through an employer with 20 or more employees, and that coverage is based on your (or your spouse's) current active employment. Every other scenario either requires immediate enrollment or triggers a permanent late-enrollment penalty.

When Delaying Part B Is Safe

You can delay Part B without a penalty when all three conditions are true:

1. You have group health coverage through an employer. The coverage must come from an employer-sponsored group health plan — not an individual marketplace plan, not COBRA, not retiree health benefits.

2. The coverage is based on current active employment. Either you're actively working for the employer, or your spouse is. The key word is "current." Once employment ends, the protection ends.

3. The employer has 20 or more employees. If the employer has fewer than 20 employees, Medicare becomes the primary payer at 65. Your employer plan drops to secondary status, and you need Part B immediately.

When all three boxes are checked, you're in a protected category under Medicare Secondary Payer rules. Your employer plan is primary, Medicare is secondary, and you have no obligation to enroll in Part B. When you eventually leave that employer (or lose the coverage), you'll get an 8-month Special Enrollment Period to sign up for Part B with no penalty.

When Delaying Part B Will Cost You

You have COBRA coverage. COBRA starts after active employment ends. It doesn't matter that you're still paying premiums to the same insurer — it's continuation coverage, not active employment coverage. Your 8-month SEP started when your active employment ended, not when COBRA will expire. If your COBRA runs 18 months and you wait until it ends to enroll in Part B, you've already blown past your SEP window.

You have retiree health benefits. Some employers continue health coverage for retirees as a benefit. This is generous, but it doesn't protect you from the Part B penalty. Retiree coverage isn't based on current active employment, so Medicare is primary over it. Without Part B, the retiree plan pays secondary to nothing — and your penalty clock is running.

You work for a small employer. If your employer has fewer than 20 employees, Medicare is primary starting at 65. Your employer plan is secondary. Without Part B, you have no primary payer for outpatient services. The employer plan may deny or severely reduce claims, and you're accumulating a 10% penalty for every full year of delay.

You have marketplace (ACA) insurance. Health insurance purchased through the federal or state marketplace does not protect you from the Part B penalty. Marketplace plans don't qualify as employer group health plans under the Special Enrollment Period rules.

The Math of Delaying

The Part B late-enrollment penalty adds 10% to your standard premium for every full 12-month period you could have had Part B but didn't. It's permanent — you pay it for as long as you're enrolled in Medicare.

With the 2026 standard Part B premium at $202.90:

The surcharge figures below are unrounded percentage calculations; Medicare rounds the total Part B premium to the nearest $0.10.

• 1 year delayed: 10% penalty = $20.29/month extra, $243.48/year
• 2 years delayed: 20% penalty = $40.58/month extra, $486.96/year
• 5 years delayed: 50% penalty = $101.45/month extra, $1,217.40/year

And because the penalty is a percentage of the standard premium, it grows every year as the base premium increases. A 20% penalty on a $202.90 premium is $40.58 today, but when the premium rises to $250 in a few years, that same 20% penalty becomes $50/month.

How to Protect Yourself During the Delay

If you're currently delaying Part B with qualifying employer coverage, do these things now — not when you retire:

Verify your employer's size. Count all employees, not just those on the health plan. If the company is anywhere near the 20-employee mark, confirm the count in writing with HR.

Get your creditable coverage in writing. Ask your employer for a letter confirming that your group health plan is based on current active employment and that it provides creditable drug coverage. Keep this letter with your important documents.

Know your 8-month window. The Special Enrollment Period starts the month after your employment ends or the month after your employer group health plan coverage ends, whichever comes first. Mark that date. Filing the day your coverage ends isn't too early — waiting 9 months is too late.

Save every document. W-2s, pay stubs, insurance cards, benefits enrollment confirmations, creditable coverage notices. You'll need these to complete Form CMS-L564 when you enroll.

The Medicare Late-Enrollment Penalties and Special Enrollment guide includes a penalty calculator, a headcount audit worksheet, and the complete CMS-L564 filing packet to make sure you transition from employer coverage to Medicare without triggering a lifetime surcharge.

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