How and When to Enroll in Medicare in 2025

Updated 12/5/2024

Medicare application and Medicare enrollment are terms that are often used interchangeably but refer to the same process of signing up for Medicare benefits.

Medicare has several different enrollment periods and eligibility rules that are unique to each part of Medicare, as well restrictions on the types of plans that can be purchased during each Medicare enrollment period. 

This Medicare enrollment guide contains all the information you’ll need about when, how and what to sign up for so you can make the most of your 2025 Medicare enrollment periods, health care benefits and coverage opportunities. 

There are six different types of Medicare sign up periods, with different actions you can take during each period, such as enrolling in a new Medicare plan or switching form one type of plan to another. 

When people ask "What is Medicare open enrollment,” they are most often referring to the fall Medicare open enrollment period for Medicare Advantage plans and Part D prescription drug plans, sometimes also referred to as the Annual Enrollment Period, or AEP.

The 2024 Medicare open enrollment starts on October 15, and Medicare enrollment ends on December 7. These dates stay the same each year. 

This is the only time of year many Medicare beneficiaries will be able to make changes to their 2025 Medicare coverage, so it's important to compare your plan local options to see if a Medicare plan in your county or city offers the right mix of benefits and coverage for your needs.

What are the Medicare open enrollment dates in 2025? 

• Oct. 15 to Dec. 7, the same dates every year

Who is the open enrollment Medicare period for in 2025?

• Those who are already enrolled in either Original Medicare (Parts A and B) or a private Medicare plan

What can you do?

• You can sign up for or switch Medicare plans during Medicare open enrollment 2024 (for your 2025 coverage), including the following options
  
  
  
  • Enroll in a Medicare Advantage plan
  • Enroll in a Medicare Part D plan
  • Switch from one Medicare Advantage plan to another
  • Switch from one Part D plan to another
  • Drop a Medicare Advantage plan and returning to Original Medicare
  • Drop a Part D plan 

Everyone who becomes eligible for Medicare is given an Initial Enrollment Period (IEP), which represents your very first opportunity to enroll in coverage. 

So, what age are you eligible for Medicare? Your Initial Enrollment Period begins on the first day of the month that is three months before the month that you turn 65 years old.

• For example, if you turn 65 on July 15^th, your Initial Enrollment Period will begin on April 1st (three months before your birthday month).
  
  
• Your Initial Enrollment Period then includes the month of your birthday and continues for another three months, for a total of seven months. 

In the example above, your Initial Enrollment Period would begin April 1 and end October 31 (three months after your birthday month). 

Many people may continue working when they turn 65. If you have health insurance through your or your spouse's employer or union, or if you have other group health plan coverage, you may qualify for a Medicare Special Enrollment Period even after your Medicare IEP is over.

When are you Medicare Eligible? 

• Begins three months before your 65th birthday and ends three months after

Who is a Medicare IEP for?

• U.S. citizens and legal permanent residents who are three months away from turning 65 years old

What you can do? 

• Sign up for Medicare Part A and Part B (Original Medicare) for the first time
• Enroll in a Medicare Advantage (Part C) plan, a Medicare Prescription Drug Plan (Part D) or a Medicare Supplement Insurance (Medigap) plan

If you sign up for Medicare prior to your 65^th birthday month, your coverage will begin on the first day of your birthday month. (If your birthday is on the first day of the month, your coverage will begin on the first day of the previous month.)

If you enroll during or after your 65^th birthday month, your coverage will begin on the first day of the following month.

If you have Original Medicare or a Medicare Advantage plan without drug coverage, you can consider enrolling in a Medicare Part D standalone Prescription Drug Plan (PDP).

Whether you're new to Medicare or if you already have a Part D plan but want to compare your plan options before the upcoming fall open enrollment period, you can get a free quote online or call to chat with a licensed insurance agent and compare plans.

If you aren’t happy with your Medicare Advantage plan, you can do drop the plan and switch to another Medicare Advantage plan or revert to Original Medicare during the Medicare Advantage Open Enrollment Period. This enrollment period lasts from January 1 to March 31 each year. 

When is the Medicare Advantage open enrollment period? 

• Jan. 1 to March 31

Who is the MA open enrollment period for?

• Those who are enrolled in a Medicare Advantage plan

What you can do?

• Switch to a different Medicare Advantage plan or drop your plan and switch to Original Medicare
• If you drop your Medicare Advantage plan (whether or not the plan offered prescription drug coverage), you may sign up for a Part D Medicare drug plan  

This enrollment period is your first opportunity to enroll in Medicare Supplement Insurance, or Medigap. This is also the best time to apply for a Medigap plan, for reasons we’ll explain below

Your Medigap Open Enrollment Period begins the day that you are at least 65 years old and enrolled in both Medicare Part A and Part B. Your Medigap Open Enrollment Period lasts for six consecutive months.

For many people, their Medicare Supplement open enrollment period takes place around the same time as their Initial Enrollment Period.  

You may still purchase a Medigap plan after your Medigap OEP has ended. As mentioned above, however, your best time to apply for a Medigap plan is during your open enrollment period.

During your Medigap Open Enrollment Period, you have what are called guaranteed issue rights. When you have guaranteed issue rights, insurance companies can’t use medical underwriting (medical exams and/or health questions) to determine your eligibility or plan premiums.

If you apply for a Medicare Supplement plan during this enrollment period, insurers are prohibited from basing your rates on your health, and you will be offered a standard rate for the plan.

There may be other qualifying life circumstances that allow you to have guaranteed issue rights at other times outside of your Medigap Open Enrollment Period. While you can apply for a Medigap plan at any time of the year, you’re typically better off doing so when you have guaranteed issue rights.

When is your Medigap open enrollment period? 

• Begins the day you are 65 or older and enrolled in Part A and Part B. It lasts for six months

Who is a Medigap open enrollment period for?

• Those who are at least 65 years old and enrolled in Medicare Part A and Part B

What you can do?

• Sign up for a Medicare Supplement Insurance (Medigap) plan

If you didn’t enroll in Original Medicare Part A and Part B during your Initial Enrollment Period, you may be able to do so during the 2025 Medicare General Enrollment Period that lasts from January 1 to March 31 each year.

When Medicare General Enrollment?

• January 1 to March 31 every year

Who is the Medicare General Enrollment period for? 

• Anyone who is eligible for Medicare but did not enroll during their Initial Enrollment Period

What you can do?

• Sign up for Medicare Part A and/or Part B
• You may not enroll in Medicare Advantage or Medicare Part D during this enrollment period unless you're eligible to enroll through a Special Enrollment Period or your Initial Enrollment Period
  
  

Special Enrollment Periods do not have fixed dates and may be granted at any time throughout the year to beneficiaries who experience certain hardships or qualifying life events.

For example, if you move to a new state that isn’t part of the service area of your current Medicare plan, you will be given a Special Enrollment Period so that you can join a plan that utilizes the doctors and hospitals in your new place of residence. 

When is a Medicare Special Enrollment Period? 

• Varies on a case-by-case basis

Who is a Medicare SEP for? 

• Medicare beneficiaries who experience a qualifying life event that may include (but is not limited to):
  
  
  
  • Moving to a new area
  • Losing or gaining eligibility for Medicaid
  • Losing employer-sponsored coverage
  • Having a plan that terminates its contract with Medicare

What can you do? 

• Varies depending on your individual circumstances

Every year, the Centers for Medicare & Medicaid Services (CMS) uses a five-star rating system to rate the quality of all Medicare Advantage and Medicare Part D. Five-star plans represent the highest quality plans, while plans with a three star rating are considered average. 

From December 8 to November 30 of the following year, those who live in an area with a five-star Medicare Advantage plan available can switch to that plan if they are currently enrolled in a plan that is rated less than five stars. 

When the five star open enrollment period? 

• December 8 to November 30 of the following year, each year

Who is the five star open enrollment period for? 

• Medicare Advantage plan members who are enrolled in a plan rated fewer than five stars

What can you do?

• Switch to a top-rated five-star Medicare Advantage plan, if one is available where you live
  
  

Some Medicare enrollment periods are based on a person being 65 years old. But what about those who are under 65?

• You may be eligible to enroll in Medicare if you are under 65 years old and have a qualifying disability. If you have collected disability benefits from Social Security or the Railroad Retirement Board for 24 consecutive months, you become eligible to sign up for Medicare during your 25th month of receiving such benefits. 
  
  
• If you have End Stage Renal Disease (ESRD) or ALS (Lou Gehrig’s disease), there is no 24-month waiting period, and you are eligible to enroll in Medicare immediately. 
  
  
• Those under the age of 65 may be eligible to enroll in Medicare Part D plans and Medicare Advantage plans if they’re eligible for Original Medicare.
  
  A Special Needs Plan is a type of Medicare Advantage plan that is designed specifically for someone with a particular health condition or disability. These plans contain a set of benefits that may be attractive to someone under the age of 65 who has a chronic health condition or is dual-eligible for Medicare and Medicaid.  

Those under the age of 65 are also eligible to enroll in Medigap, although not every beneficiary will be able to do so. The decision to offer Medigap to those under age 65 is left up to each state, and not every state requires insurers to do so. 

The following 34 states require insurers who sell Medigap to offer at least some of their plans to Medicare beneficiaries who are under age 65. In some states, all Medigap plans sold by a company will be available to those under 65. Premiums for plans in some states may be higher for those under 65.

• Arkansas
• California
• Colorado
• Connecticut
• Delaware
• Florida
• Georgia
• Hawaii
• Idaho
• Illinois
• Indiana
• Kansas
• Louisiana
• Maine
• Maryland
• Massachusetts
• Michigan
• Minnesota
• Mississippi
• Missouri
• Montana
• New Hampshire
• New Jersey
• New York
• North Carolina
• Oklahoma
• Oregon
• Pennsylvania
• South Dakota
• Tennessee
• Texas
• Vermont
• Virginia
• Wisconsin

In all other states there are no requirements for insurance companies to sell plans to those under 65 years old. 

Most people are automatically enrolled in Medicare Part A and Part B once they become eligible, but others may have to manually sign up for Medicare. 

• If you are collecting retirement or disability benefits from Social Security or the Railroad Retirement Board, you will be automatically enrolled in Medicare Part A and Part B as soon as you become eligible and will receive a “Welcome to Medicare” packet in the mail. This typically happens around three months before your 65^th
  
  
• If you choose to delay your Social Security or Railroad Retirement Board benefits and are not yet collecting those payments when you turn 65, you will not be automatically enrolled and must sign up manually online, over the phone or at your local Social Security office.   

One important thing to note: Medicare Part B enrollment is optional. If you qualify for automatic Medicare enrollment, you will be enrolled in Part B and then given instructions on how to opt out of Part B if you wish.

Each type of Medicare coverage comes with its own eligibility rules. 

Original Medicare

What it is: Original Medicare is made up of two parts.

• Part A is hospital insurance. It covers hospital costs and other inpatient care.
• Part B is medical insurance. It covers outpatient care like doctor’s appointments, medical equipment and supplies, outpatient treatments, certain vaccines and more. 

Original Medicare requires you to be at least 65 years old or have a qualifying disability. You must be a U.S. citizen or permanent legal resident of at least five years to be eligible for Medicare.

Medicare Advantage

What it is: Medicare Advantage, or Medicare Part C, provides all of the same benefits as Medicare Part A and Part B while also typically adding coverage for some things not covered by Original Medicare.

Some of these extra benefits can include things such as dental, vision and hearing care, prescription drugs and/or gym memberships. 

In order to join a Medicare Advantage plan, you must be enrolled in both Medicare Part A and Part B and live in the area in which your desired plan is sold. 89% of 2024 Medicare Advantage plans cover prescription drugs, and more than 97% of plans offered one or more of the benefits listed above.¹

The fall open enrollment period may be the only chance you have to compare plans and find a new Medicare Advantage plan with more benefits, wider network coverage or lower costs than your current plan.

Medicare Part D

What it is: Medicare Part D provides coverage for prescription medications. 

In order to be eligible for a Medicare Part D plan, you must first either be enrolled in either Medicare Part A or Part B (or both).

You may enroll in a Part D plan if you are enrolled in a Medicare Advantage plan that does not provide prescription drug coverage. However, you are not eligible for Part D if you are enrolled in a Medicare Advantage plan that already includes prescription drug benefits.

Lastly, you must reside in the area in which your desired plan is sold. 

Medicare Supplement Insurance

What it is: Medicare Supplement Insurance, or Medigap, provides coverage for deductibles, copayments, coinsurance and various other out-of-pocket costs required by Medicare Part A and Part B. 

To apply for a Medigap plan, you must be enrolled in both Medicare Part A and Part B and live in the area in which the desired plan is sold. 

If you qualify for automatic enrollment into Original Medicare, you should receive your “Welcome to Medicare” packet to arrive in the mail. This will include your Medicare card, Medicare handbook and all other enrollment materials. 

If you do not qualify for automatic enrollment, sign up manually online, over the phone or in person at a Social Security office. 

For Medicare Advantage, Medicare Part D and Medicare Supplement Insurance, contact an insurance agent who is licensed to sell plans in your area to compare policies, discuss your options and get enrolled. 

¹ Freed M, et al. (Nov. 15, 2023). Medicare Advantage 2024 Spotlight: First Look. Kaiser Family Foundation. https://www.kff.org/medicare/issue-brief/medicare-advantage-2024-spotlight-first-look.

² Centers for Medicare & Medicaid Services. (Oct 13, 2023). Fact Sheet: 2024 Medicare Advantage and Part D Star Ratings. https://www.cms.gov/newsroom/fact-sheets/2024-medicare-advantage-and-part-d-star-ratings.