Medicare enrollment periods explained: Don’t miss your window for 2026

Medically reviewed by Kelsey Mueckl, RN, BSN

Are you getting ready to turn 65, or helping someone who is? Then you’ve probably heard about Medicare. Medicare is a type of health insurance for people 65 and older, and some younger people with disabilities. It helps pay for doctor visits, hospital stays, and even medicine.

Medicare isn’t just something you sign up for once and forget about it. There are special times when you can join, switch, or drop your Medicare plan. These times are called enrollment periods and understanding them is very important. If you miss your chance, you might have to pay a penalty or go without coverage for a while.

So, what are the 3 enrollment periods for Medicare?

• Initial Enrollment Period (IEP)
• Annual Enrollment Period (AEP)
• Special Enrollment Period (SEP)

Each enrollment period has its own rules and timeline. Keep reading to learn more, get prepared, and avoid missing your enrollment window.

What are the different parts of Medicare?

Before we dive into enrollment periods, let’s quickly review the different parts of Medicare. Think of them like different pieces of a puzzle that fit together to give you the health care coverage you need.

What is Original Medicare?

Original Medicare includes:¹

• Part A (hospital insurance): This helps cover your costs when you’re in the hospital, a skilled nursing facility, or getting hospice care. Most people don’t pay a monthly premium for Part A if they’ve worked and paid Medicare taxes for at least 10 years.
• Part B (medical insurance): This helps cover doctor visits, outpatient care, and preventative services like screenings and vaccines. Most people pay a monthly premium for Part B.

You can also add:

• Part D (prescription drug coverage): This helps pay for your prescription medications. It’s offered by private insurance companies that Medicare approves.
• A Medigap policy: This helps pay for things Original Medicare doesn’t cover, like copays and deductibles.

What is Medicare Advantage (Part C)?

Medicare Advantage is a private plan that replaces Original Medicare. It covers Part A and Part B and often includes Part D (prescription coverage). Many plans also offer extra benefits like vision, dental, and hearing.¹

You can only have Original Medicare or a Medicare Advantage Plan—but not both.

You need both Medicare Part A and Part B to join a Medicare Advantage Plan (Part C).

You need either Medicare Part A or Part B to join a standalone Medicare drug plan (Part D).

What is the Medicare Initial Enrollment Period?

The Initial Enrollment Period (IEP) is your first opportunity to sign up for Medicare. This isn’t something you can do just any time—Medicare gives you a specific window to enroll when you first become eligible.

This window lasts for 7 months and centers around your 65th birthday. The period starts 3 months before the month you turn 65, includes the month you do turn 65, and then goes on for 3 months after you turn 65.²

Let’s break it down with some examples:

• If your birthday is in July: Your Initial Enrollment Period starts in April and ends in October.
• If your birthday is in December: Your Initial Enrollment Period starts in September and ends in March of the following year.

Why is the Initial Enrollment Period important?

If you miss signing up during your IEP, you may have to wait to enroll later—and you could pay more each month in penalties.

What if you’re still working at 65?

If you have health insurance through your job (or your spouse’s job), you might be able to wait to sign up for Part B without a penalty. See more on this below under Special Enrollment Periods.

What is the Medicare Annual Enrollment Period?

The Annual Enrollment Period, or AEP, happens every year. This is your annual chance to make changes to your existing Medicare coverage.

The Medicare Annual Enrollment Period happens every year from October 15 to December 7.²

During this time, you can:

• Switch from Original Medicare (Parts A and B) to a Medicare Advantage Plan (Part C).
• Switch from a Medicare Advantage Plan back to Original Medicare.
• Change your Part D drug plan.
• Switch from one Medicare Advantage plan to another.

If you’ve already enrolled in a Medicare Advantage Plan, you may also take advantage of the Medicare Advantage Open Enrollment Period, which occurs every year from January 1 to March 31.² During this time, you can either switch to another Medicare Advantage Plan or drop your Medicare Advantage Plan and go back to Original Medicare.

Why is the Medicare AEP important?

Your health needs change over time—so can your plan’s costs, coverage, and drug list. The AEP lets you choose what’s best for your current health and budget.

Any changes you make during the Annual Enrollment Period start January 1 of the following year.

What is the Medicare Special Enrollment Period?

Sometimes life brings changes—like moving, losing health coverage, or retiring. In these cases, Medicare gives you a Special Enrollment Period (SEP) to make changes.

When can you get a Medicare SEP?

Here are some common reasons for a Special Enrollment Period:²

• You move to a new area where your current plan doesn’t work.
• You lose other health coverage, like from a job.
• You move into or out of a nursing home or long-term care facility.
• Your current plan stops working in your area.
• You get Medicaid or Extra Help and your situation changes.

Each situation has its own rules about how long you have to make changes—usually up to 2 months after the event occurs.

What changes can I make during a Special Enrollment Period?

Depending on your situation, you may be able to:

• Join a Medicare Advantage Plan
• Switch back to Original Medicare
• Add, drop, or change a drug plan

Why is the Medicare SEP important?

SEPs give you flexibility when something big changes in your life. They help make sure you don’t go without coverage.

Medicare enrollment tips for caregivers

If you’re helping a loved one who is either on Medicare or about to become eligible, there are many ways you can help them:

Mark key dates on a calendar:

• The 7-month IEP
• October 15–December 7 for AEP
• Any SEP dates if a major change happens
  • Review their plan each year to make sure it still fits their health needs.
  • Look out for mail in the fall—plans often send letters if there are changes.
  • Call Medicare or use the website (www.medicare.gov) to get help comparing plans.

Medicare enrollment periods can feel confusing at first, but once you know the basics, it gets easier. Just remember:

• IEP = When you first turn 65
• AEP = Every year from October 15–December 7
• SEP = When life changes

Signing up at the right time helps you avoid penalties and keeps your health care on track. If you need help, you can always call Medicare at 1-800-MEDICARE.

Staying informed means staying covered—and that means peace of mind for both seniors and those who care for them.

Sources:

• “Parts of Medicare,” Medicare.gov, last accessed August 5, 2025, https://www.medicare.gov/basics/get-started-with-medicare/medicare-basics/parts-of-medicare.
• “Understanding Medicare Advantage & Medicare Drug Plan Enrollment Periods,” Medicare.gov, last accessed August 5, 2025, https://www.medicare.gov/publications/11219-Understanding-Medicare-Advantage-Medicare-Drug-Plan-Enrollment-Periods.pdf