Do You Need Medicare Part B — And What Happens If You Don't Enroll

Medicare Part B covers doctor visits, outpatient care, and preventive services — but it is not automatic, and waiting to enroll can cost you

Medicare Part B is optional, but the decision to skip it or delay it has real consequences. Part B pays for visits to doctors and specialists, outpatient hospital services, diagnostic tests, and preventive care like cancer screenings and vaccines. If you turn 65 and do not enroll in Part B when you first become may be able to access, you will pay a permanent penalty on your monthly premium — even if you join years later. The only way to avoid that penalty is to have other coverage that counts as "creditable" — usually employer health insurance or TRICARE — during the months you are not on Part B.

Most people do need Part B. If you are retired and have no employer coverage, or if your employer coverage is ending, Part B is how you pay for doctor care under Medicare. If you are still working and covered by your employer's plan, you may be able to delay Part B without penalty, but only if your employer has 20 or more employees. If your employer is smaller, you must enroll in Part B when you turn 65 or face the penalty.

Key Takeaways

Part B is optional but carries a permanent 10 percent penalty for each year you delay enrollment after age 65, unless you have creditable coverage like employer insurance.
You can delay Part B without penalty only if you are covered by an employer health plan with 20 or more employees, or by TRICARE or the VA.
Your initial enrollment period is the three months before you turn 65, the month you turn 65, and the three months after — missing this window triggers the penalty unless you have creditable coverage.
Part B costs a monthly premium (the standard amount in 2024 is $164.90, but higher earners pay more), plus a yearly deductible and coinsurance on services.
If you enroll late without creditable coverage, you will pay the penalty for as long as you are on Medicare, even if you later switch to a plan that covers Part B.

When you can delay Part B without penalty

You can put off enrolling in Part B past age 65 without facing a penalty if you have creditable coverage — health insurance that is at least as good as Medicare Part B. The most common form is employer health insurance. If your employer has 20 or more employees and covers you, you can delay Part B. The same applies if your spouse is still working and covers you under their employer plan with 20 or more employees.

TRICARE (military health coverage for retirees and their families) and the Department of Veterans Affairs (VA) also count as creditable coverage. If you are covered by either, you can delay Part B. Federal employees covered by the Federal Employees Health Benefits Program (FEHB) can also delay. Once your creditable coverage ends — because you retire, leave the job, or your employer drops the plan — you have eight months to enroll in Part B without penalty. That eight-month window is called your Special Enrollment Period.

If you are unsure whether your coverage counts as creditable, contact your health plan directly and ask. Do not assume. If you delay Part B without creditable coverage, the penalty applies for life.

How the late enrollment penalty works

The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but not enrolled. In 2024, the standard premium is $164.90 per month. If you delay one year, you pay an extra $16.49 per month forever. If you delay five years, you pay an extra $82.45 per month for the rest of your life on Medicare. The penalty stacks on top of whatever your actual premium is — and your actual premium may be higher than the standard amount if your income is above a certain threshold.

The penalty does not go away. Even if you enroll in Part B later and then switch to a different plan, the surcharge follows you. The only exception is if you can prove you had creditable coverage during the months you were not enrolled. You will need documentation from your former health plan showing the dates of coverage.

If you believe you were penalized in error — for example, because you had creditable coverage but the Social Security Administration did not record it — you can request a review. Contact Social Security and bring proof of your coverage. The process takes time, so do not count on a refund.

Your initial enrollment period and what happens if you miss it

Your Initial Enrollment Period (IEP) runs for seven months: the three months before the month you turn 65, the month you turn 65, and the three months after. If you enroll during this window, your coverage starts on the first day of the month you turn 65 (or the first of the following month if you enroll in the month you turn 65). If you enroll after your IEP ends and you do not have creditable coverage, your coverage will not start until the month after you enroll, and the penalty begins to accrue.

Social Security will automatically enroll you in Part B during your IEP if you are already receiving Social Security benefits. If you are not yet receiving benefits, you must enroll yourself — Social Security does not do it automatically. You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

If you miss your IEP and do not have creditable coverage, you can still enroll, but you will face the penalty. There is no second chance to avoid it unless you can document creditable coverage.

What Part B actually costs

Part B has three costs: the monthly premium, an annual deductible, and coinsurance. The standard monthly premium in 2024 is $164.90, but it changes each year and is higher for people with income above $97,000 (single) or $194,000 (married filing jointly). The higher income thresholds are based on your tax return from two years prior, so if your income was high in 2022, you will pay more in 2024.

Once you meet the yearly deductible (which is $240 in 2024), you typically pay 20 percent coinsurance for most services — doctor visits, lab work, imaging, and outpatient hospital care. Some preventive services, like annual wellness visits and cancer screenings, have no cost. Part B does not cover dental, vision, or hearing care, and it does not cover prescription drugs (that is Part D).

Many people buy a Medigap (supplemental insurance) policy to cover the deductible and coinsurance that Part B does not pay. Medigap premiums vary widely depending on the plan and your age, but they typically range from $100 to $300 per month. If you enroll in a Medicare Advantage plan instead of Original Medicare, you do not need Medigap, but you will have different out-of-pocket costs and network restrictions.

Part B and Medicare Advantage: which path to take

Part B is the foundation of Original Medicare. If you choose Original Medicare, you must have Part B to access doctor care. If you choose a Medicare Advantage plan (Part C), you are still technically enrolled in Part B — it is bundled into the Advantage plan — but you do not pay a separate Part B premium. Instead, you pay the Advantage plan's premium (which may be zero) and your out-of-pocket costs are determined by the plan's design.

The choice between Original Medicare with Part B and Medigap versus Medicare Advantage depends on your health, your doctors, and your budget. Original Medicare gives you access to any doctor or hospital that accepts Medicare. Medicare Advantage usually requires you to use doctors and hospitals in the plan's network, but it may have lower out-of-pocket costs if you use a lot of care. If you are healthy and want flexibility, Original Medicare with Part B may suit you. If you have chronic conditions and want predictable costs, Medicare Advantage may be better.

Whichever path you choose, you must enroll in Part B during your Initial Enrollment Period or have creditable coverage. You cannot avoid Part B entirely without consequences.

Frequently Asked Questions

Can I enroll in Part B after I turn 65 if I do not have creditable coverage?

Yes, you can enroll anytime, but you will pay a permanent penalty on your monthly premium. The penalty is 10 percent of the standard premium for each year you delayed. If you wait five years to enroll, you will pay 50 percent more than the standard premium for the rest of your life on Medicare.

What counts as creditable coverage?

Creditable coverage is health insurance at least as good as Medicare Part B. Employer health insurance (if your employer has 20 or more employees), TRICARE, the VA, and the Federal Employees Health Benefits Program all count. Individual or family plans you buy yourself do not count. If you are unsure, ask your health plan directly.

If I am still working at 65, do I have to enroll in Part B?

Not if your employer has 20 or more employees and covers you. You can delay Part B as long as you are covered by that employer plan. Once you retire or lose that coverage, you have eight months to enroll in Part B without penalty. If your employer has fewer than 20 employees, you must enroll in Part B when you turn 65.

What happens if I enroll in Part B and then change my mind?

You can drop Part B, but if you do and do not have creditable coverage, you will face a penalty if you enroll again later. The only exception is if you drop Part B to enroll in a Medicare Advantage plan, which includes Part B coverage. If you drop Part B for any other reason, think carefully before doing so.

Does Part B cover prescription drugs?

No. Part B covers doctor visits, outpatient care, and preventive services. Prescription drugs are covered by Part D, which is a separate enrollment. You must enroll in Part D during your Initial Enrollment Period or when you first become may be able to access, or you may face a penalty if you enroll later without creditable drug coverage.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.