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Medicare Enrollment Periods

Table of Contents

Summary: Individuals who are eligible for Medicare can only enroll in coverage during specific time periods, known as Medicare enrollment periods. Some enrollment periods occur annually, while some only occur once. Understanding enrollment periods is essential for making sure you get your coverage when you need it. Estimated Read Time: 4 min

How Does Medicare Enrollment Work?

The Medicare enrollment process begins once you become eligible for Medicare coverage. Once you become eligible for Medicare, you will either get coverage automatically, or you will need to sign up for your coverage. For those who need to manually enroll in Medicare, you must do so during specific timeframes.

Just because you qualify for Medicare coverage does not mean you can enroll in Medicare at any time. Whether you’re enrolling in Original Medicare, a Medicare Advantage plan, a Medicare Part D Prescription Drug plan, or a Medicare Supplement plan, you must do so during a valid Medicare enrollment period.

What are Medicare Enrollment Periods?

Medicare enrollment periods are specific timeframes in which you can enroll in or change Medicare coverage. Some enrollment periods for Medicare occur annually, while others may only occur once in your lifetime.

Medicare enrollment periods that occur annually:

  • Medicare Annual Enrollment Period
  • Medicare General Enrollment Period
  • Medicare Advantage Open Enrollment Period

Medicare enrollment periods that typically only occur once or have special requirements:

  • Initial Enrollment Period
  • Medicare Supplement Open Enrollment Period
  • Special Enrollment Period

Each enrollment period will have a deadline in which you must sign up for your Medicare coverage. If you miss the deadline, you will need to wait until the next valid enrollment period to enroll in coverage.

For example, if you do not enroll in Medicare Part B before your Initial Enrollment Period ends, you will have to wait until the General Enrollment Period to enroll.

There is an exception: those who qualify for a $0 premium Medicare Part A can enroll in their Part A coverage any time after becoming eligible for Medicare. If you do not enroll in Medicare Part A during your Initial Enrollment Period, you do not need to wait until another enrollment period to sign up.

Medicare Enrollment Periods Chart

In the chart below, we’ll break down which parts of Medicare you can enroll in during each enrollment period. Please note that some of these enrollment periods will vary from person to person.

Medicare Part AMedicare Part BMedicare Advantage PlanMedicare Part D Prescription Drug PlanMedicare Supplement Plan
Initial Enrollment Period
(7 months; differs from person to person)
Annual Enrollment Period
(Oct 15th – Dec 7th)
General Enrollment Period
(Jan 1st – Mar 31st)
Medicare Advantage Open Enrollment Period
(Jan 1st – Mar 31st)
Medicare Supplement Open Enrollment Period
(Begins on Part B effective date; lasts six months after)
Special Enrollment Period
(63 days following a qualifying event)

*You must already be enrolled in a Medicare Advantage plan to sign up for a different Advantage plan during the Medicare Advantage Open Enrollment Period.

As you can see in the chart above, the Initial Enrollment Period differs from other enrollment periods since you can enroll in Original Medicare as well as any additional Medicare plans. Outside of that period, you will need to consider which coverage you want to sign up for and wait for an appropriate enrollment period.

Why Understanding Medicare Enrollment Periods is Important

Having a basic understanding of Medicare, including Medicare enrollment periods, is important for making sure you get the coverage you need, when you need it. Below are a few reasons why understanding Medicare enrollment periods is so important:

  1. Each enrollment period has different rules regarding which coverage you can enroll in during that period. If you’re planning on picking up additional coverage, or changing Medicare plans, you need to know which enrollment periods are valid to do so.
  2. If you miss a Medicare enrollment period, you could be left with gaps in your coverage. Each enrollment period will have a deadline for signing up for coverage. If you miss your Medicare enrollment period deadline, you will have to wait until the next valid enrollment period to sign up for coverage. This could mean going months without the healthcare coverage you need.
  3. You may face late enrollment penalties if you don’t sign up for coverage at the right time. For some, this may be during the Initial Enrollment Period. For others, it may be during a Special Enrollment Period.

Each enrollment period works a little differently. If you are looking for more information about a specific Medicare enrollment period, you can check out our resources below.

How to Get Help with Medicare Enrollment

Whether you’re planning on sticking with Original Medicare, or are interested in supplemental coverage, it’s important to enroll on time. We understand that the timeframes and rules for Medicare enrollment periods can get confusing. That’s why we help Medicare enrollees every day with understanding their Medicare options and how to get the coverage they need. If you have questions regarding Medicare enrollment, call us at the number above to speak to a licensed insurance agent.


Medicare & You 2024, Medicare. Accessed November 2024


Thomas Liquori

Thomas Liquori

Ashlee Zareczny

Ashlee Zareczny

Compliance Supervisor and Licensed Medicare Agent
Ashlee Zareczny is the Compliance Supervisor for ApplyforMedicare. As a licensed Medicare agent in all 50 states, she is dedicated to educating those eligible for Medicare by providing the necessary resources and tools. Additionally, Ashlee trains new and tenured Medicare agents on CMS compliance guidelines. Ashlee is a Medicare expert who specializes in Medicare Supplement, Medicare Advantage, and Medicare Part D education.