Do You Have to Sign Up for Medicare Part B?

Medicare Part B is not automatic — you have to sign up for it, but the timing and consequences depend on your situation

Medicare Part A (hospital insurance) starts automatically when you turn 65 if you are already receiving Social Security or Railroad Retirement benefits. Part B (medical insurance for doctor visits, outpatient care, and preventive services) does not. You must actively sign up for Part B, either when you first become may be able to access at 65 or during a specific enrollment window. If you miss that window and do not have other coverage, you will face a permanent penalty on your premiums for as long as you have Medicare.

The rule has exceptions. If you are still working and covered by your employer's health plan, you can delay Part B without penalty. If you are a federal employee, a railroad retiree, or covered by TRICARE (military health insurance), different rules explore. Understanding which path fits your situation now can save you money and prevent gaps in coverage later.

Key Takeaways

Part B enrollment is not automatic; you must sign up during your Initial Enrollment Period (the three months before, the month of, and three months after your 65th birthday) or face a permanent 10% premium increase for each year you delay.
If you have health coverage through your current employer, you can delay Part B without penalty as long as you enroll within eight months of losing that coverage or retiring.
Federal employees, railroad retirees, and TRICARE beneficiaries have different enrollment rules and should contact their specific agency rather than Medicare directly.
You can sign up for Part B through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
If you miss your enrollment window and do not have employer coverage, you will pay a higher premium permanently unless you can prove you had good cause for the delay.

When you must sign up for Part B

Your Initial Enrollment Period runs for seven months: the three months before the month you turn 65, the month you turn 65, and the three months after. For example, if you turn 65 in June, your enrollment period is March through September. You can sign up anytime during this window, and coverage will begin on the first day of the month you turn 65 (or the first day of the following month if you sign up after your birthday month).

If you do not sign up during this seven-month window, you enter what Medicare calls the General Enrollment Period, which runs January 1 through March 31 each year. Coverage would not start until July 1 of that year — a gap of several months. More importantly, you will owe a late enrollment penalty: a permanent 10% increase to your Part B premium for each full year you delayed after your Initial Enrollment Period ended. That penalty stays with you for life, even if you eventually sign up.

The only way to avoid this penalty if you miss your Initial Enrollment Period is to prove you had good cause — a circumstance beyond your control that prevented you from signing up. Medicare rarely accepts this claim, and you must provide documentation. Examples include severe illness, language barriers, or incorrect information from a government employee. straightforward not knowing about the important date is not considered good cause.

If you have employer health insurance, you can delay Part B

If you are still working at 65 and your employer offers health insurance, you can turn down Part B without penalty. Your employer coverage counts as creditable coverage — insurance that is at least as good as Medicare Part B. You have eight months from the date you lose that coverage (through retirement, job loss, or the employer plan ending) to sign up for Part B without owing a late penalty.

This eight-month window is separate from your Initial Enrollment Period. If you are 67 and still covered by your employer, you can sign up for Part B during the General Enrollment Period (January through March) with no penalty, as long as you lost your employer coverage within the past eight months. Once you lose employer coverage, count the months carefully — the eight-month clock starts the month after coverage ends.

You will need to prove you had employer coverage when you sign up. Have your health plan documents or a letter from your employer's benefits department ready. Medicare will ask for this proof, and without it, they may assess a late penalty even if you did have coverage.

Special rules for federal employees, railroad workers, and military beneficiaries

Federal employees and federal retirees covered by the Federal Employees Health Benefits Program (FEHB) can delay Part B while covered by FEHB. You have a special enrollment period after FEHB coverage ends. Contact your FEHB plan or the Office of Personnel Management (OPM) for the exact timeline — it differs from the standard eight-month rule.

Railroad Retirement beneficiaries have their own enrollment rules through the Railroad Retirement Board. If you receive Railroad Retirement benefits, do not rely on standard Medicare enrollment periods. Contact the Railroad Retirement Board directly at 1-877-772-5772 to confirm when and how to sign up for Part B.

TRICARE beneficiaries (active-duty family members, retirees, and survivors) can delay Part B while TRICARE coverage is active. Once TRICARE ends, you have a special enrollment period to sign up for Part B without penalty. Contact TRICARE or your military health benefits office for your specific enrollment window.

How to sign up for Part B

You can sign up for Part B through three routes: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. The online method is fastest — you can complete it in about 10 minutes if you have your Social Security number and Medicare number (or birth date and citizenship information) ready.

When you sign up, you will choose a start date for your coverage. If you sign up during your Initial Enrollment Period, coverage typically begins the first of the month you turn 65. If you sign up after that window, coverage begins the first of the month following your process, or later if you request it.

You will also see the monthly premium amount for Part B. This premium is deducted from your Social Security check each month (or billed separately if you do not receive Social Security). The premium amount varies by income and changes each year.

What happens if you miss the important date

If you do not sign up during your Initial Enrollment Period and do not have employer coverage or another may have access to reason to delay, you will face consequences. The most significant is the late enrollment penalty — a permanent 10% increase to your Part B premium for each year you were may be able to access but not enrolled. If you delayed for three years, your premium would be 30% higher than the standard rate, and that increase never goes away.

You can still sign up during the General Enrollment Period (January through March), but coverage will not start until July 1 — leaving you uninsured for several months. During that gap, you are responsible for the full cost of any doctor visits, tests, or outpatient care. If you have a serious health event during those months, the bills can be substantial.

If you believe you have good cause for missing the important date, you can request a review. Contact Medicare at 1-800-MEDICARE and ask to speak with someone about a late enrollment penalty appeal. Have documentation ready — medical records, letters from employers, or proof of language barriers. Approval is not may provide, but it is worth attempting if you have a legitimate reason for the delay.

Frequently Asked Questions

Can I sign up for Part B after I turn 65 if I do not need it yet?

Yes, but only during your Initial Enrollment Period (three months before through three months after your 65th birthday). If you wait beyond that window and do not have employer coverage or another may have access to reason, you will owe a late penalty. If you have employer insurance, sign up within eight months of losing it to avoid the penalty.

What if I am still working past 65 and my employer does not offer health insurance?

You should sign up for Part B during your Initial Enrollment Period, even if you are still working. Without employer coverage, you do not have an exception to the enrollment important date. Delaying Part B without coverage will result in a permanent premium penalty.

Do I have to sign up for Part D (prescription drug coverage) at the same time as Part B?

No. Part B and Part D have separate enrollment periods. However, if you delay Part D beyond your Initial Enrollment Period without creditable drug coverage, you will also face a late penalty on your drug plan premium. It is often simpler to enroll in both during the same window, but they are separate decisions.

If I sign up for Part B, do I have to drop my employer health insurance?

No. You can have both Part B and employer coverage at the same time. In fact, if you are still working and covered by your employer, you should keep that coverage and delay Part B. Once you retire or lose the employer plan, enroll in Part B within eight months to avoid penalties.

What if I missed my enrollment important date years ago and never signed up?

You can still sign up during any General Enrollment Period (January through March), and coverage will begin July 1. You will owe a late penalty based on how many years you delayed. Contact Medicare to discuss your situation and whether you might have grounds to appeal the penalty based on good cause.

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.