Medicare Enrollment Periods: When Do You Sign Up for Medicare?

HealthCare Writer

Updated on November 2nd, 2021

Reviewed by Diane Omdahl

We aim to help you make informed healthcare decisions. While this post may contain links to lead generation forms, this won’t influence our writing. We follow strict editorial standards to give you the most accurate and unbiased information.

What You Need to Know

For most people, nearing their 65th birthday is the best time to sign up for Medicare Part A, hospital insurance, and Part B, medical insurance, also called Original Medicare. Enrolling during the seven-month Initial Enrollment Period around your birthday will help avoid coverage gaps and penalties for late enrollment. 

If you’re 65 and have medical benefits through your employer or your spouse’s job, you may be able to delay signing up without paying a penalty. When that coverage ends, you’ll be eligible for a Special Enrollment Period that lasts eight months.

Once you’ve signed up for Original Medicare, you can enroll in a Medicare Advantage plan, also known as Part C. These plans often include prescription drug insurance.

If you decide to stay with Original Medicare, you can buy a standalone Part D prescription drug policy and a Medicare Supplement Insurance (also known as a Medigap policy).

If your 65th birthday is approaching, it’s time to figure out when to apply for the various parts of Medicare to ensure you’re fully covered when you need it.

Most people should apply for Medicare in the seven-month Initial Enrollment Period (IEP) surrounding their birthday. That’s the three months before their 65th birthday, the month of their birthday and the three months following their birthday. 

Suppose you don’t sign up for Medicare when first eligible, and you don’t qualify for an exception. In that case, you can enroll in Medicare Part A and/or B during the General Enrollment Period (GEP). The General Enrollment Periods runs from January 1 to March 31 each year. In this case, your coverage will start on July 1. Keep in mind that you might have to pay a higher monthly premium for late enrollment in Part A and/or Part B. 

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There’s also the fall Open Enrollment Period, which runs from October 15 through December 7 annually. (This is also called the Annual Election Period.) You can sign up for Part D, prescription drug coverage, change Medicare Advantage plans and switch between Original Medicare and Medicare Advantage (more on that below). 

Below are four steps to guide you in enrolling in the various parts of Medicare, including the best times to sign up for each.

Step 1: Sign Up for Original Medicare (Part A and B) 

Most Americans need to sign up for Medicare Part A, hospital insurance, and Medicare Part B, medical insurance when they reach 65. You can do so online or through your Social Security office. (Together, Parts A and B are also called Original Medicare.) 

In most cases, you won’t receive Medicare benefits automatically unless you sign up. But if you already receive benefits from Social Security or the Railroad Retirement Board, you’ll be automatically enrolled.

If you don’t enroll in Part B during the seven months around your 65th birthday, your Initial Enrollment Period, you could incur a penalty. 

There is an exception, though: If you’re still working and have health coverage through your job, you can sign up for Part A, which usually involves no premium, and you may be able to delay signing up for Medicare Part B (and paying the premium for this coverage). To avoid penalties for delayed enrollment, you must have medical coverage through your or your spouse’s job.

If you or your spouse have worked for at least 10 years, you typically won’t pay a premium for Medicare Part A coverage.

When Does Medicare Part A and B Coverage Start?

To avoid a gap in coverage, sign up for Medicare Part A and Part B in the three months before your 65th birthday. If you do, your coverage will start in your birthday month. 

If you sign up toward the middle or end of your Initial Enrollment Period, your coverage will start from one to six months after your birthday month, depending on when you enroll.

If You Missed Enrolling Your Initial or General Enrollment Period?

If a group health plan covers you through your or your spouse’s employer or union, you can sign up for Medicare Part A or Part B anytime. 

If your employment or group health plan ends, you have an eight-month Special Enrollment Period to sign up for Part A and Part B without facing a late enrollment penalty. Keep in mind that retiree health plans and COBRA don’t qualify you for a Special Enrollment Period when that coverage ends. 

If You Have a Disability, ESRD or ALS

Americans with a disability who have received Social Security disability benefits for 24 months are automatically enrolled in Medicare Part A and Part B. Automatic enrollment also applies to beneficiaries who have serious illnesses such as end-stage renal disease, ESRD, and amyotrophic lateral sclerosis, ALS. You’ll receive your card when you qualify.

 You don’t need to do anything to sign up.

Similarly, if you’ve received disability benefits from the Railroad Retirement Board for 24 months, you’ll be enrolled automatically in Medicare Parts A and B. 

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Step 2: Decide on Medicare Advantage (Part C)

Now that you’ve enrolled in Medicare Part A and Part B, you need to decide whether you want to stay with Original Medicare, Parts A and B, or sign up for Medicare Part C, also called Medicare Advantage

With a Medicare Advantage plan, you continue to pay a premium for Part B while a private insurance carrier delivers your services. That company contracts with Medicare to deliver both Part A and Part B benefits. Policies vary, but most include prescription drug coverage and other benefits that aren’t covered by Original Medicare. You enroll with a private insurer to get your Part C/Advantage plan. You can compare plans at

When Can You Enroll in Medicare Advantage?

You can enroll in Medicare Advantage during your Initial Enrollment Period. But you must first sign up for Parts A and B during your Initial Enrollment Period. 

You can also enroll if you qualify for a Special Enrollment Period. If you lose your health insurance at your job, you can sign up for a plan up to eight months after losing your coverage. 

When Does Medicare Advantage Coverage Start? 

If you enroll in Medicare during the General Enrollment Period (January 1 to March 31 each year), you can sign up for Medicare Advantage between April and June. The coverage starts on July 1. 

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Step 3: Choose Coverage for Prescription Drugs (Part D)

Once you’ve completed Steps 1 and 2, you’re ready to decide about your drug coverage.

Medicare doesn’t cover the cost of most prescription drugs. Still, there are two ways to sign up for insurance that will help pay for your medications: If you stay on Original Medicare, Parts A and B, you can buy a standalone policy specifically for prescription drug coverage. This policy is called a Medicare Part D prescription drug plan

Or, if you opt for a Medicare Advantage plan, prescription drug insurance is often included. offers a tool to compare and shop for Part D and Medicare Advantage plans.

When Can You Enroll in Prescription Drug Coverage?

You have a few options as to when you can sign up.

  • Your Initial Enrollment Period: This occurs when you first become eligible for Medicare
  • Open Enrollment Period (or Annual Election Period): From October 15 to December 7 each year, you can enroll in a prescription drug plan. 
  • Medicare Advantage Open Enrollment Period: From January 1 to March 31 each year, if you are already enrolled in a Medicare Advantage plan without drug coverage, you can switch to a plan that includes the coverage.
  • Special Enrollment Period: Certain events, like moving or losing your insurance coverage, make you eligible to enroll outside the usual times.

Step 4: Consider Whether You Need Medicare Supplement Insurance

You might already know that Medicare doesn’t pay 100% of approved charges. For example, Medicare Part B coverage pays 80% of covered medical costs after you meet the annual deductible. That means you’re responsible for the remaining 20% and for paying your deductible. 

That’s why many people who choose Original Medicare also buy Medicare Supplement Insurance, often called a Medigap policy, to help pay for some or all of these “gaps” in benefits. Private insurance companies sell these policies. They help pay for other costs, including coinsurance and copays.

When Can You Buy a Medigap Policy?

Once you’re age 65 and enrolled in Medicare Part B for the first time, you have a six-month Medigap Open Enrollment Period in which you can buy a Medigap policy. During this period, you can buy any Medigap policy sold in your state, even if you have health problems (i.e., a preexisting condition like colon cancer or diabetes). 

If, though, you apply for Medicare Supplement Insurance after your Medigap Open Enrollment Period, you could be turned down for a policy if you have certain health conditions. 

When Does Your Medigap Policy Coverage Begin?

Once you receive your Medicare card, you can apply for a Medigap policy. It’s best to apply as soon as you have your Medicare card. If you apply one to three months before your 65th birthday month, that will allow enough time for your application to be processed and will also ensure your Medicare Supplement Insurance coverage begins the same month that Medicare kicks in for you.

Next Steps

Indeed, figuring out when and how to enroll in all aspects of Medicare can take some time and attention. But by signing up in a timely way, you’ll save yourself extra work and ensure you’re covered when you really need it—and that you’ve chosen the plans that will work best for your budget and medical situation. 

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  1. My Medicare Matters. “When Does Medicare Coverage Start?” (accessed August 25, 2020).

  2. U.S. Government Website for Medicare. “When Can I Buy Medigap Insurance?” (accessed August 25, 2020).

  3. National Council on Aging. “Medigap Open Enrollment Period.” (accessed August 25, 2020).