You don't have to take Medicare Part B, but waiting to sign up later usually costs you more in premiums for the rest of your life

Medicare Part B covers doctor visits, outpatient care, and medical equipment. It is not automatic — you have to choose it during your initial enrollment window, which is the three months before you turn 65, the month you turn 65, and the three months after. If you don't sign up then and you don't have other coverage that counts as "creditable," you will pay a late enrollment penalty added to your Part B premium every month going forward.

The penalty is 10 percent of the standard Part B premium for each 12-month period you were may be able to access but did not sign up. That penalty stays with you permanently — it does not go away after a few years. So if you wait five years to enroll, you pay 50 percent extra on top of your regular premium for life.

There are narrow exceptions: if you have health insurance through your job or your spouse's job, or if you are covered by a federal employee health plan, you can delay Part B without penalty as long as that coverage lasts. You must sign up within eight months of losing that job-based coverage, or the penalty applies.

Key Takeaways

  • Part B is optional at 65, but skipping it without job-based coverage triggers a permanent 10 percent monthly penalty for each year you delay.
  • Your initial enrollment window is three months before you turn 65, the month of your birthday, and three months after — missing it is the most common reason people pay penalties.
  • If you have health insurance through an employer or union, you can delay Part B without penalty as long as that coverage continues.
  • Once you lose job-based coverage, you have eight months to enroll in Part B penalty-free; after that, the penalty applies permanently.
  • You can enroll in Part B during the General Enrollment Period (January 1 to March 31 each year), but any penalty you owe starts the month after you enroll.

When you can skip Part B without a penalty

The only situation where you can turn down Part B at 65 without facing a lifetime penalty is if you have creditable coverage — health insurance through your current job, your spouse's current job, or a federal employee health plan. The coverage must be active and must cover at least as much as Medicare Part B does. COBRA coverage (continuation coverage after job loss) counts, but only while you are actively using it.

If you have this kind of coverage, you can delay Part B. But you must enroll within eight months of the date your job-based coverage ends. That eight-month window is your protection against the penalty. After eight months, if you have not signed up, the 10 percent monthly penalty kicks in and never stops.

Part-time work, self-employment, or coverage through a spouse's part-time job may or may not count as creditable coverage — it depends on the details of the plan. If you are unsure, contact Medicare at 1-800-MEDICARE before your coverage ends. They can tell you whether your specific plan qualifies.

What happens if you miss your initial enrollment window

Your initial enrollment window closes three months after your 65th birthday. If you do not sign up during those seven months and you do not have job-based coverage, you have missed the window with no penalty protection.

You can still enroll, but only during the General Enrollment Period, which runs January 1 through March 31 each year. If you enroll during this period, your coverage starts July 1 of that year, and your penalty begins the month your coverage starts. The longer you wait, the larger the penalty grows.

For example: if you turn 65 in June 2024 and do not sign up, you miss your window in September 2024. If you enroll in the General Enrollment Period in February 2025, your coverage starts July 2025, and you owe a 10 percent penalty (for the one-year period you were may be able to access but not enrolled). If you wait until February 2027 to enroll, you owe a 20 percent penalty (for two years).

How the late enrollment penalty is calculated

The penalty is not a one-time fee — it is a permanent increase to your monthly Part B premium. Medicare calculates it as 10 percent of the standard Part B premium amount for each 12-month period you were may be able to access but did not enroll.

The standard Part B premium changes each year. In 2024, it is $164.90 per month for most people, though higher earners pay more. A 10 percent penalty on that amount is about $16.49 per month. If you delay five years, your penalty is about $82.45 per month — on top of whatever the standard premium is at that time. That penalty is added to your bill every single month for the rest of your life, even if you move, change plans, or reach a different age.

The only way the penalty stops is if you go a full 12 months without any break in Part B coverage. If you drop Part B and later re-enroll, the penalty calculation resets, but you will owe a new penalty for the time you were not enrolled.

Special enrollment periods that waive the penalty

If you missed your initial enrollment window for a specific reason — such as a serious illness, a move to a new state, or a mistake by Medicare or Social Security — you may be able to enroll in a Special Enrollment Period without penalty. These are not automatic; you have to contact Medicare and explain your situation.

Common reasons Medicare accepts include: you were out of the country, you received incorrect information from Medicare or Social Security, you had a change in your immigration status, or you lost coverage due to a life event (like divorce or loss of a job). You must contact Medicare within the timeframe they specify for your situation — usually within a few months of the event.

To request a Special Enrollment Period, call 1-800-MEDICARE or visit your local Social Security office with documentation of your reason. Having a good reason does not may provide approval, but it is worth asking if you believe you have a legitimate circumstance.

Deciding whether Part B makes sense for your situation

Even though you can skip Part B, the financial math usually favors signing up. The late enrollment penalty is permanent and grows quickly. Unless you have job-based coverage that will continue indefinitely, or you are certain you will never use doctor services, the penalty cost over time exceeds the cost of straightforward enrolling at 65.

If you are still working and have employer coverage, review your plan documents or call your benefits office to confirm it is creditable coverage. If it is, you can safely delay Part B. But mark your calendar for eight months after you leave that job — that is your important date to enroll penalty-free.

If you are retired or self-employed without group coverage, enrolling during your initial window is almost always the lower-cost choice. The standard Part B premium is the same whether you enroll at 65 or at 75; the penalty is what makes waiting expensive.

How to enroll in Part B

You can enroll in Part B through Social Security, Medicare, or your local Social Security office. During your initial enrollment window (three months before to three months after your 65th birthday), you can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your Social Security office.

If you are already receiving Social Security benefits, Part A (hospital insurance) is usually automatic at 65, but Part B is not. You have to actively choose it. If you are not yet receiving Social Security, you will need to contact Social Security to enroll in Part B even if you do not want your benefits yet.

Have your Social Security number and information about any current health coverage ready when you enroll. The process takes about 10 minutes by phone or online. Your coverage will start the first of the month after you enroll (or the first of your birth month if you enroll during your initial window).

Frequently Asked Questions

Can I enroll in Part B after I turn 65 if I missed my window?

Yes, but only during the General Enrollment Period (January 1 to March 31 each year). Your coverage will start July 1, and you will owe a late enrollment penalty. The penalty is 10 percent of the standard Part B premium for each year you were may be able to access but not enrolled.

Does my spouse's job-based insurance count as creditable coverage for me?

Yes, if you are covered under your spouse's active health plan. You can delay Part B without penalty as long as that coverage continues. When your spouse retires or loses that job, you have eight months to enroll in Part B penalty-free.

What if I enrolled in Part B but then dropped it — do I have to pay a penalty to re-enroll?

Yes. If you drop Part B and later re-enroll, you will owe a new late enrollment penalty for the months you were not enrolled. The only exception is if you dropped it to use a Medicare Advantage plan or other Medicare coverage — in that case, you may not owe a penalty when you switch back.

Is the late enrollment penalty the same for everyone?

The penalty percentage is the same (10 percent per year), but the dollar amount depends on the standard Part B premium, which changes each year. Higher-income beneficiaries also pay a higher base Part B premium, so their penalty is larger in dollar terms.

Can I get the late enrollment penalty removed if I made a mistake?

Not usually. The penalty is permanent unless you can show you had a valid reason to miss your enrollment window and you request a Special Enrollment Period. Contact Medicare to explain your situation — they will review it, but approval is not may provide.