Still working at 65? Whether you can safely delay Part B depends on your employer’s size and the type of coverage you have. Here is how the rules work and where the penalties come in.

This guide is general information, not insurance, tax or legal advice. Rules, limits and deadlines change each year, so check HealthCare.gov, Medicare.gov or your insurer for your situation.

Turning 65 while you are still working raises one of the most common Medicare questions: can you keep the insurance you have, or do you have to sign up? The answer depends on where your coverage comes from, how large your employer is, and what happens when that coverage ends. Timing matters, because some mistakes produce penalties that last as long as you have Medicare. No one is required to enroll at 65, but the rules reward people who plan ahead.

Can I Delay Part B While Working With Employer Coverage?

Often, yes. If you or your spouse are still working and covered under a group health plan from that job, you can wait to sign up for Part B without paying a late enrollment penalty. When the employment or the coverage ends, whichever comes first, you get an 8-month Special Enrollment Period to sign up for Part B, or to add it to Part A you already have.

Two details trip people up. The group plan must be available to everyone at the company, and it must come from a current job. Retiree coverage, COBRA, severance packages and individual plans do not count as active employment coverage, even when they look much the same. If you want a refresher on how the pieces fit together, our Medicare basics guide covers Parts A through D and when each one usually starts.

Prescription drugs follow a similar rule. You can delay Part D without a penalty if your job-based drug coverage is creditable, meaning it is at least as good as Medicare’s. Your insurer should tell you whether the coverage is creditable. If you go 63 days or more without creditable drug coverage after your first chance to enroll, a penalty is added to your premium for as long as you have drug coverage.

Does My Employer’s Size Change the Answer?

It usually does. At an employer with 20 or more employees, the job-based plan is generally the primary payer, so you can usually delay Part B. At an employer with fewer than 20 employees, you will probably need to sign up for Part B when first eligible, because Medicare is generally expected to pay first.

Your coverage at 65	Can it stand in for Part B while you delay?
Group plan from your or a spouse’s current job, 20 or more employees	Generally yes
Group plan from an employer with fewer than 20 employees	Usually no
COBRA continuation coverage	No
Retiree coverage from a former employer	No
Marketplace or other individual plan	No

Ask your benefits administrator one direct question: does the plan expect Medicare to be primary or secondary once you turn 65? If Medicare is expected to pay first and you have not enrolled, bills you assumed the job plan would cover can land on you.

What Happens If I Sign Up for Part A but Not Part B?

Usually nothing bad, because Part A is premium-free for people who, or whose spouse, paid Medicare taxes for at least 40 quarters, the equivalent of 10 years. Many workers take premium-free Part A at 65 and delay Part B until their job coverage ends. Once work stops, the same 8-month Special Enrollment Period applies to adding Part B.

If you do not qualify for premium-free Part A, the math changes. You would pay a monthly premium, and if you buy Part A late, your premium goes up 10 percent, and you pay the higher amount for twice the number of years you went without signing up. If you do sign up for Part A late, coverage can be backdated up to 6 months, though never earlier than the month you turned 65.

Also ask your employer what happens to your job-based benefits if you enroll in Part A but not Part B. Some plans will not pay for services unless you have both.

How Does COBRA Fit In After I Leave My Job?

COBRA is a federal law that can let you keep your employer group plan for a limited time after employment ends, generally 18 months and in some cases 36. It generally applies to employers with 20 or more employees, and some states have mini-COBRA laws that extend similar rights to workers at smaller companies, so check with your state insurance department.

For Medicare purposes, though, COBRA is not the same as having a job. It does not let you delay Part B, and it does not extend your Special Enrollment Period. The 8 months run from when you stopped working or lost your job-based coverage, whether or not you take COBRA. Two more wrinkles matter. If you are eligible for Medicare but not enrolled, a COBRA plan may pay only a small share of your care and leave you most of the bill. And once you do sign up for Medicare, your COBRA will probably end. Our article on COBRA versus the Marketplace explains what happens to job-based coverage when a job ends.

Important: A Special Enrollment Period is tied to active employment, not to COBRA, retiree coverage or severance. Missing the 8-month window can mean waiting until the next General Enrollment Period and paying a Part B penalty for life.

What If I Have a High-Deductible Plan and an HSA?

This is a situation where people often choose to delay, so check how enrolling in Part A or Part B would affect your HSA contributions before you sign up. Our guide to HSAs and high-deductible plans explains how these accounts work day to day. If your situation is unusual, for example you are self-employed or your plan is not offered to everyone at the company, ask your insurer whether the coverage counts as employer group health plan coverage as the IRS defines it. If it does not, the safer path is generally to sign up for Medicare at 65 rather than risk the Part B penalty.

How Do I Enroll or Delay Without Missing a Deadline?

Start with your Initial Enrollment Period, the 7 months that begin 3 months before the month you turn 65 and end 3 months after. If you miss it and later lose your route to a Special Enrollment Period, you must wait for the General Enrollment Period, January 1 to March 31, and coverage starts the month after you sign up.

The Part B penalty for delaying without qualifying coverage is an extra 10 percent of the standard premium for each full 12 months you waited. Wait 24 months and the penalty is 20 percent. In 2026, a 2-year delay works out to the standard $202.90 monthly premium plus a $40.58 penalty, or $243.50 a month for as long as you have Part B. The Part D penalty differs: 1 percent of the national base beneficiary premium, $38.99 in 2026, for each month without creditable drug coverage.

Marketplace coverage follows its own path. If you buy a plan there, sign up for Medicare at 65 and tell the Marketplace, because eligibility for premium tax credits ends when your Part A coverage begins.

Where Can I Get Free Help With the Decision?

You do not have to work this out alone. State Health Insurance Assistance Programs, known as SHIPs, offer free counseling on exactly this decision. Social Security handles Part A and Part B enrollment and can confirm your timeline at 800-772-1213 or at a local office. Medicare.gov has a short questionnaire that tells you when to sign up based on the type of coverage you have. If you have retiree coverage from a former employer, ask the benefits administrator how it coordinates with Medicare, since retiree plans may not pay unless you have both Part A and Part B.

A practical next step is to ask your benefits administrator two questions, whether your plan is group coverage available to everyone at the company and whether Medicare would be the primary payer, then confirm your enrollment window with Social Security or your SHIP before you decide.

Frequently asked questions

Do I have to sign up for Medicare at 65 if I’m still working?
No, no one is required to enroll at 65. Whether delaying is safe depends on having group coverage from a current job at an employer with 20 or more employees.

Does COBRA count as job coverage for delaying Part B?
No. For Medicare purposes, COBRA is not active employment coverage and does not qualify you for the Special Enrollment Period. Your 8-month window runs from when you stopped working, whether or not you take COBRA.

What is the Part B late enrollment penalty?
It is an extra 10 percent of the standard premium for each full 12 months you could have enrolled but did not. The penalty is charged for as long as you have Part B.

Can I delay just Part B and keep Part A?
Yes, and many working people do. Premium-free Part A is available to those with 10 years of Medicare taxes, and you can add Part B later during the 8-month Special Enrollment Period.