You turn 65, you're still on your employer's plan, and you figure you'll sort out Medicare later. That logic works fine if you do it right. Get it wrong and you could pay a penalty on your Part B premium every month for the rest of your life.
The Medicare Part B late enrollment penalty adds 10% to your monthly premium for each full 12-month period you were eligible but didn't sign up. Miss two years: 20% penalty. Miss five years: 50% penalty. The standard Part B premium in 2026 is $202.90 per month. Add a 50% penalty and you're paying over $300 a month, every month, for coverage that would have cost $202.90 if you'd enrolled on time.
The penalty doesn't expire. It follows you for as long as you have Medicare Part B. And because the base premium typically rises each year, the dollar amount of your penalty tends to creep up right along with it.
When you have to sign up
Most people become eligible for Medicare at 65. Your first chance to enroll is a 7-month window called the Initial Enrollment Period, which opens three months before your birthday month, includes your birthday month, and closes three months after. If you're already collecting Social Security, you're enrolled in Parts A and B automatically and your card arrives in the mail before you turn 65.
If you miss this window without a valid reason, the next regular opportunity is the General Enrollment Period, which runs January 1 through March 31 each year. Coverage begins the following month. Every full 12-month stretch you went without Part B and without qualifying coverage gets added to your penalty calculation. That gap can grow quickly if you don't realize what's happening.
The good news is that missing the Initial Enrollment Period doesn't automatically mean a penalty. Whether you owe one depends on why you were late and what coverage, if any, you had in the meantime.
The one situation where delaying is actually fine
If you or your spouse is still actively working when you turn 65, and you're covered under a group health plan through that current employer, you can delay Part B without penalty. The key word is “current.” Coverage must be tied to active employment, not a former job, not retiree benefits, not COBRA.
When that job-based coverage ends, you get an 8-month Special Enrollment Period to sign up for Part B. That window opens the day your employment ends or your group health plan coverage ends, whichever happens first. You don't need to wait until the coverage actually lapses. In fact, it's smarter to submit your enrollment forms while you're still covered so there's no gap when Part B kicks in.
One important note for people at smaller companies: if your employer has fewer than 20 employees, Medicare becomes your primary insurance at 65 even if you stay on the job plan. In that case, you generally should enroll in Part B during your Initial Enrollment Period regardless of your employment status, or the employer plan may cover very little.
The COBRA trap
This is where a lot of people get hurt. You retire at 65, your employer offers COBRA, you sign up for 18 months of continued coverage, and you assume you're protected. You're not.
COBRA is not creditable coverage for purposes of avoiding the Part B penalty. Only health insurance from a current employer, meaning someone is still actively working, qualifies you for a Special Enrollment Period. Once you retire and your employment ends, the 8-month Part B enrollment clock starts ticking whether you take COBRA or not. If you ride out COBRA for 18 months before enrolling in Part B, you'll owe a 10% penalty for that gap. Retiree health plans from a former employer carry the same problem: they don't count as active-employment coverage, and they don't pause the penalty clock.
The mistake is understandable. COBRA feels like real insurance, because it is real insurance. It just isn't the kind of coverage that lets you delay Medicare enrollment without consequence.
How the penalty is calculated
The math is straightforward. For each full 12-month period you were eligible for Part B but didn't enroll and didn't have qualifying coverage, 10% is added to the standard monthly premium. Partial years don't count; Medicare only counts complete 12-month periods.
At the 2026 standard premium of $202.90, here's what the penalty adds up to:
- 1 year late: $20.29 extra per month ($223.20 total)
- 2 years late: $40.58 extra per month ($243.48 total)
- 5 years late: $101.45 extra per month ($304.35 total)
- 7 years late: $142.03 extra per month ($344.93 total)
Those figures are for 2026. The base premium generally rises each year, which means the dollar value of your penalty typically rises with it. Someone who delayed by five years and now pays a 50% surcharge will see that surcharge amount increase every time premiums go up.
Who is exempt from the penalty
A few groups either avoid the penalty or have it waived entirely.
If you qualify for a Medicare Savings Program, your state pays your Part B premiums and late enrollment penalties are waived. These are income-based programs designed for people with limited resources. If you're also enrolled in Medicaid, your state covers the premiums and any penalties as well.
If you enrolled in Medicare before 65 due to a disability and were paying a late penalty at the time, the penalty stops when you turn 65 and your eligibility shifts from disability to age. You essentially get a clean slate at 65.
People who lived outside the United States and its territories during the years they missed may also qualify for a penalty-free Special Enrollment Period when they return. And in some cases, if someone delayed enrollment because of genuinely bad advice from an official source, Medicare may grant equitable relief and waive the penalty. That's not a routine process, but it does exist.
What to do if you've already missed the window
If you've missed your Initial Enrollment Period and don't have a qualifying reason for the delay, your options are limited but not zero.
First, check whether you qualify for a Special Enrollment Period. If you or your spouse has active employer coverage, that coverage may still allow you to delay or to enroll now without penalty. If the job-based coverage has already ended, count backward: you have 8 months from when that coverage ended. If you're still inside that window, enroll now.
If you've already triggered a penalty, check your eligibility for a Medicare Savings Program in your state. Income limits vary by state, but qualifying removes the penalty entirely going forward. Your State Health Insurance Assistance Program (SHIP) can walk you through this at no cost. Find your local SHIP counselor through shiphelp.org.
If you believe you were penalized because of incorrect advice from Social Security or another official source, you can request equitable relief through the Social Security Administration by calling 1-800-772-1213. It doesn't always work, but it's worth asking.
The practical checklist
Most people who end up with a lifetime penalty didn't intend to skip Medicare. They were working, they had coverage, and they didn't realize the rules had strict limits on what qualifies as a valid reason to wait. Here's the short version of what to confirm before you delay:
- Is the coverage through a current employer, not a former one?
- Is someone in your household actively employed, not just receiving retiree benefits?
- Does the employer have 20 or more employees?
- Are you relying on COBRA, which does not count?
- Do you have a plan to enroll in Part B within 8 months of when employment or coverage ends?
If any of those answers are unclear, a free SHIP counselor can help you confirm your situation before you miss a deadline you can't take back.
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