Medicare Part B Late Enrollment Penalty: How It Works and How to Avoid It

The Part B late enrollment penalty is one of the most expensive Medicare mistakes because it usually lasts for as long as you have Part B. The good news: it’s very avoidable if you know your windows.

I’m Michael Cubell, a licensed independent agent with Triangle Life & Health (licensed since 2013, NPN 16899969). I help people in 15 states sort through Medicare every day. Here’s the plain-English version.

How the Part B Penalty Is Calculated

Your monthly premium goes up 10% for each full 12-month period you were eligible for Part B but didn’t sign up. Only full 12-month periods count.

Example

Say your Initial Enrollment Period ended, and you waited 27 months to sign up. That’s only two full 12-month periods, so your penalty is 20%.

	2026 amount
Standard Part B premium	$202.90/month
20% penalty	+$40.58/month
Your premium with penalty	about $243.50/month

That extra amount follows you every year, and it’s based on that year’s standard premium, so it grows as Part B premiums rise.

When You Can Delay Part B Without a Penalty

If you (or your spouse) are still working and covered by a group health plan based on that current employment, you can usually delay Part B. When the job or the coverage ends (whichever happens first), you get an 8-month Special Enrollment Period to sign up with no penalty.

These do NOT count as coverage from current employment:

• COBRA
• Retiree health coverage
• VA coverage
• Individual or Marketplace (ACA) coverage
• Former-employer coverage through severance or a layoff

COBRA is the big trap. Your 8-month window starts when your employment ends, not when COBRA ends. If you ride COBRA for 18 months, you can miss the window completely.

Missed Your Window? Here’s What Happens

You can sign up during the General Enrollment Period, January 1 – March 31 each year. Coverage starts the first day of the month after you sign up. You may owe the penalty. If you missed your window because of something outside your control (like a natural disaster, an employer or health plan error, or losing Medicaid), you may qualify for an exceptional-circumstances Special Enrollment Period.

Turning 65 soon? Start with my Turning 65 Medicare checklist. If you’re dropping employer drug coverage too, see how the Part D penalty works.

Frequently Asked Questions

How much is the Medicare Part B late enrollment penalty?

Your Part B premium goes up 10% for each full 12-month period you could have had Part B but didn’t sign up. In 2026, a 20% penalty adds $40.58 a month to the $202.90 standard premium.

Is the Part B penalty permanent?

In most cases, yes. You’ll pay it for as long as you have Part B. People who qualify for a Medicare Savings Program may not have to pay it.

Can I delay Part B if I’m still working?

Usually, yes. If you or your spouse have group health coverage based on current employment, you can delay Part B. You’ll have 8 months after the job or the coverage ends, whichever comes first, to sign up without a penalty.

Does COBRA count as creditable coverage for Part B?

No. COBRA isn’t coverage based on current employment, so it doesn’t protect you from the Part B penalty. Your 8-month window starts when your job ends, even if you’re on COBRA.

When can I sign up for Part B if I missed my Initial Enrollment Period?

During the General Enrollment Period, January 1 to March 31 each year, unless you qualify for a Special Enrollment Period. Coverage starts the month after you sign up.

Questions? Let’s Talk It Through

Working past 65, or retiring soon and not sure when to start Part B? Let’s map out your dates. Call me at (919) 944-8443 or schedule a free consultation. No pressure, just straight answers.

📞 Call (919) 944-8443