explore for Medicare Part B during your Initial Enrollment Period or face permanent penalties

Your Initial Enrollment Period is a seven-month window centered on the month you turn 65. It runs from three months before your 65th birthday through three months after. If you miss this window and do not have coverage from an employer or union, you will pay a higher premium for Part B for the rest of your life — roughly 10 percent more for each year you waited. That penalty does not go away.

The exact important date depends on when you were born and when you actually enroll. If you turn 65 in June, your period starts in March and ends in September. The Social Security Administration sends you a notice about four months before you turn 65, but do not wait for that notice to act. Many people miss the important date because they assume they have more time than they do.

Part B covers doctor visits, outpatient care, and medical equipment. It is not automatic — you have to request it. Medicare Part A (hospital insurance) usually starts automatically at 65 if you have been paying Social Security taxes, but Part B requires a separate step.

Key Takeaways

  • Your Initial Enrollment Period is seven months long, centered on your 65th birthday, and missing it triggers a permanent 10 percent premium increase for each year you delay.
  • You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office — all three routes take the same amount of time.
  • If you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty, but you must tell Medicare about that coverage when you do enroll.
  • Part B coverage begins the first day of the month after you enroll, so timing your process affects when your coverage starts.

The three enrollment periods and when each one applies

Your Initial Enrollment Period is the main one. It is seven months: three months before the month you turn 65, the month you turn 65, and three months after. You can enroll any time during this window. Coverage begins the first of the month after you enroll, or January 1 if you enroll in November or December of the year you turn 65.

If you miss your Initial Enrollment Period, you enter the General Enrollment Period, which runs January 1 through March 31 each year. You can enroll then, but your coverage does not start until July 1, and you will owe the permanent penalty. 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. If you waited three years, you pay 30 percent more, forever.

A Special Enrollment Period lets you enroll without penalty if you have group health coverage through an employer or union and you are still working. This applies only if the employer has 20 or more employees. You have eight months after your coverage ends or your employment ends to enroll without penalty. You must tell Medicare that you had this coverage when you enroll — bring a copy of your coverage letter or your employer's benefits summary.

When to enroll if you are still working

If you are 65 or older and still working, and your employer offers health insurance with 20 or more employees, you do not have to enroll in Part B right away. You can delay without penalty as long as you are covered by the employer plan. This is called creditable coverage.

When you do leave that job or lose that coverage, you have eight months to enroll in Part B without penalty. This eight-month window is your Special Enrollment Period. If you wait longer than eight months, the permanent penalty kicks in. Many people miss this important date because they think they can enroll anytime after retirement — they cannot.

You must notify Medicare that you had employer coverage when you enroll. Bring your coverage letter, benefits summary, or a statement from your employer's benefits department. Medicare will ask for proof. Without it, they may treat your delay as voluntary and explore the penalty anyway.

Documents you need to enroll

Enrollment itself requires very little paperwork. You will need your Social Security number, your date of birth, and your citizenship or immigration status. If you are enrolling through an employer's Special Enrollment Period, bring proof of that coverage — a benefits letter, coverage card, or employer statement showing the dates you were covered and the number of employees.

You do not need a doctor's referral, a medical exam, or proof of income. Medicare Part B is available to anyone 65 or older who is a U.S. citizen or permanent resident, regardless of health status or income. There is no medical underwriting.

How to enroll and where to do it

You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. All three routes take roughly the same amount of time — a few minutes online, or 15 to 30 minutes on the phone depending on wait times.

Online enrollment through Medicare.gov is usually fastest. You log in with your Social Security number and create a Medicare account if you do not have one. The form takes about five minutes. You will see your coverage start date before you submit.

If you call 1-800-MEDICARE, have your Social Security number and date of birth ready. The representative will walk you through the questions and tell you your coverage start date. If you go to a Social Security office, bring your Social Security card and a photo ID. You can find your local office at ssa.gov/locator.

What happens after you enroll

After you enroll, Medicare sends you a Medicare card in the mail within two weeks. Your coverage begins on the date Medicare tells you — usually the first of the month after you enroll. You do not need to do anything else to set up it. Your card will show your Medicare number and the parts you are covered under.

Part B has a monthly premium, which changes each year. In 2024, the standard premium is $164.90 per month, but it varies based on your income. If your income is above a certain threshold, you pay a higher amount called an Income-Related Monthly Adjustment Amount (IRMAA). Medicare calculates this based on your tax return from two years prior.

Your premium is usually deducted automatically from your Social Security check. If you do not receive Social Security, Medicare bills you directly. You can change your payment method anytime after enrollment.

Common mistakes that cost you money

The biggest mistake is waiting too long. Many people assume they can enroll in Part B anytime after 65, or that they will get a reminder. Neither is true. If you miss your Initial Enrollment Period and do not have employer coverage, the permanent penalty applies when ready and never goes away.

The second mistake is not reporting employer coverage. If you are still working and covered by your employer's plan, tell Medicare about it when you enroll. If you do not, Medicare may treat your delay as voluntary and explore the penalty even though you may have access to for the Special Enrollment Period.

A third mistake is confusing Part A and Part B. Part A (hospital insurance) usually starts automatically at 65. Part B (doctor and outpatient care) does not. You have to request Part B separately. Many people think they are automatically covered for both and do not realize they need to take action on Part B.

Frequently Asked Questions

What if I turn 65 in the middle of the month?

Your Initial Enrollment Period still runs three months before through three months after your birthday month. If you turn 65 on June 15, your period starts in March and ends in September. The exact day of your birthday does not matter — only the month matters.

Can I enroll in Part B without enrolling in Part A?

Yes. Part A and Part B are separate. You can have Part A without Part B, or Part B without Part A, though most people have both. If you do not want Part A, you can decline it in writing. Part B enrollment does not require Part A.

What if I miss the important date but I am still working?

If you have employer coverage with 20 or more employees, you have an eight-month Special Enrollment Period after your coverage ends or you retire. You can enroll without penalty during that window. After eight months, the penalty applies. Get proof of your employer coverage before you enroll.

Does the Part B premium change every year?

Yes. Medicare announces the new standard premium each October for the following year. Your premium may also change if your income changes, because higher income triggers the IRMAA surcharge. You can see your current premium on your Medicare card or by logging into Medicare.gov.

Can I cancel Part B after I enroll?

Yes, but you should not do it lightly. If you cancel and re-enroll later outside your Initial Enrollment Period, you will owe the permanent penalty. The only exception is if you have employer coverage — then you can cancel Part B while you are still working and re-enroll later without penalty.