Enroll during your Initial Enrollment Period, which starts three months before the month you turn 65

Your Initial Enrollment Period is a seven-month window that begins three months before your 65th birthday month and ends three months after it. For example, if you turn 65 in June, your period runs from March through September. During this window, you can enroll in Medicare Part A (hospital insurance) and Part B (medical insurance) without waiting or paying a penalty later.

If you miss this window, you can still enroll, but you may face a late enrollment penalty — a permanent increase to your Part B and Part D (prescription drug) premiums. The penalty amount depends on how many months you delayed, and it stays with you for as long as you have Medicare. This is why timing matters: enrolling on schedule costs less over your lifetime.

You do not have to wait until you turn 65 to start thinking about Medicare. Many people begin looking at their options at 63 or 64, which gives them time to understand the different plans and make a choice without rushing.

Key Takeaways

  • Your Initial Enrollment Period runs for seven months: three months before, the month of, and three months after you turn 65.
  • Enrolling during this period avoids late penalties on Part B and Part D premiums that would otherwise follow you permanently.
  • If you are still working and covered by your employer's health plan, you may have a different important date — ask your employer's benefits office.
  • 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 Initial Enrollment Period, you can enroll during the General Enrollment Period (January 1 to March 31 each year), but penalties will explore.

Special enrollment periods if you have employer coverage or lose coverage

If you are still working and your employer has 20 or more employees, you and your spouse may be able to delay Medicare Part B without a penalty. This is called creditable coverage. You can stay on your employer plan and enroll in Medicare later — usually within eight months of leaving that job or losing the coverage. You will need to show proof that your employer coverage was active when you became may be able to access for Medicare.

If you lose health coverage for any reason — job loss, divorce, aging off a parent's plan — you may may have access to for a Special Enrollment Period lasting two months after the loss. This lets you enroll outside the normal windows without a penalty. You will need documentation of the coverage loss, such as a letter from your former employer or insurance company.

If you are on Medicaid or receive benefits from the Veterans Administration, different rules may explore. Contact your state Medicaid office or your VA regional office to understand how those programs interact with Medicare enrollment.

Automatic enrollment if you receive Social Security

If you are already receiving Social Security benefits when you turn 65, Medicare will enroll you automatically in Parts A and B about three months before your 65th birthday. You will receive a Medicare card in the mail. You do not need to do anything — the enrollment happens on its own.

Even if you are automatically enrolled, you still need to make a choice about prescription drug coverage (Part D) and supplemental or Medicare Advantage plans. Automatic enrollment in Parts A and B does not include these, and missing the important date for Part D can result in a penalty. You have until the end of the month in which you turn 65 to enroll in a Part D plan without penalty.

If you do not want Medicare Part B when you turn 65, you can decline it in writing. This is rare, but it is an option if you have active employer coverage and want to stay on that plan instead.

What happens if you miss your enrollment important date

If you do not enroll during your Initial Enrollment Period and you do not may have access to for a Special Enrollment Period, you can enroll during the General Enrollment Period, which runs January 1 through March 31 each year. Coverage would begin July 1 of that year. This means you could have a gap in coverage of several months.

During this gap, you are responsible for all medical costs. A hospital stay, emergency room visit, or unexpected diagnosis could result in bills you have to pay out of pocket. This is one reason why enrolling on time is important — it protects you from gaps in coverage.

Late enrollment penalties are calculated based on the number of months you were may be able to access but not enrolled. For Part B, the penalty is 10 percent of the standard premium for each 12-month period you delayed. For Part D, the penalty is 1 percent of the national average premium for each month of delay. These penalties are added to your premium each month and do not go away.

Enrolling in prescription drug coverage and supplemental plans

Part D (prescription drug coverage) has its own enrollment important date. You must enroll in a Part D plan by the end of the month in which you turn 65, or during your Special Enrollment Period if you may have access to for one. If you miss this important date and do not have other creditable drug coverage, you will pay a penalty when you eventually enroll.

You also need to decide whether to buy a Medigap (supplemental) plan or a Medicare Advantage plan. Medigap helps pay costs that Original Medicare does not cover, such as copayments and coinsurance. Medicare Advantage is an alternative to Original Medicare offered by private insurance companies. These choices do not have the same hard important date as Part A and B, but enrolling during your Initial Enrollment Period gives you the most options and the best rates.

If you enroll in a Medicare Advantage plan during your Initial Enrollment Period, you have a one-time right to switch back to Original Medicare and buy a Medigap plan during the first 12 months. After that, switching becomes harder and may require medical underwriting.

How to enroll when the time comes

You can enroll in Medicare through three main 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 website lets you compare plans side by side and enroll when ready. The phone line connects you to a representative who can answer questions and help you enroll. Social Security offices offer in-person help if you prefer to talk face-to-face.

Have your Social Security number, birth date, and citizenship or immigration status ready. If you are enrolling in a Medicare Advantage or Part D plan, you will also need to choose a specific plan — the websites and phone line can help you compare based on your doctors and medications.

Enrollment typically takes 15 to 30 minutes online or by phone. If you enroll before the 15th of the month, your coverage usually starts on the first of the next month. If you enroll after the 15th, coverage may start the following month.

Planning ahead: what to do before your enrollment period

Start gathering information about six months before you turn 65. Review your current health coverage and medications. Make a list of the doctors you see regularly and the prescriptions you take — this will help you compare plans later. If you have questions about your employer coverage or how it affects Medicare, contact your employer's benefits office or human resources department.

Visit Medicare.gov and use the plan comparison tool. You can search by your zip code and see which plans include your doctors and medications. Many plans have different costs and coverage rules, so comparing now means you will not be rushed when your enrollment period arrives.

If you are unsure about your options, contact your State Health Insurance information Program (SHIP). SHIP offers free, unbiased counseling about Medicare. You can find your local SHIP office on the Medicare website or by calling 1-800-MEDICARE.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

You can start the enrollment process up to three months before you turn 65, but coverage will not begin until the month you turn 65 or later. You cannot have Medicare coverage before you are 65 unless you have been receiving Social Security disability benefits for 24 months or have end-stage renal disease or ALS.

What if I am still working at 65?

If your employer has 20 or more employees and offers health coverage, you can delay Part B without penalty. You must enroll in Part A, but Part B can wait until you leave the job or lose coverage. Keep documentation of your employer coverage in case you need to prove it later.

Do I have to enroll in Part B if I do not want it?

You can decline Part B in writing, but if you change your mind later, you may face a late enrollment penalty unless you have a may have access to reason. Most people enroll in Part B to avoid gaps in coverage, even if they are still working.

What is the penalty for missing the important date?

The Part B penalty is 10 percent of the standard premium for each 12-month period you were may be able to access but not enrolled. The Part D penalty is 1 percent of the national average premium for each month of delay. These penalties are permanent and added to your monthly premium.

Can I change my mind after I enroll?

Yes. You have a limited time to change your Medicare Advantage or Part D plan each year during the Annual Enrollment Period (October 15 to December 7). If you enroll in Medicare Advantage during your Initial Enrollment Period, you also have one chance to switch back to Original Medicare within the first 12 months.