When Can You Sign Up for Medicare? These Enrollment Periods Can Make or Break Your Plan

Key Takeaways

• Missing the right Medicare enrollment period in 2025 could result in late penalties and gaps in coverage.

• You have multiple opportunities to enroll, but each one comes with its own rules, timelines, and eligibility criteria.

Understanding the Timing Behind Medicare Enrollment

If you’re turning 65 or becoming eligible for Medicare in another way, knowing when to sign up is critical. Enrollment isn’t automatic for everyone, and missing the correct window can mean waiting months to get coverage—or paying more for it.

Medicare has a series of enrollment periods that vary depending on your circumstances. Some happen only once, others return each year, and some are triggered by life events. It all starts with knowing which one applies to you.

1. Initial Enrollment Period (IEP)

Your first opportunity to sign up for Medicare is called the Initial Enrollment Period (IEP). This seven-month window surrounds your 65th birthday month.

• Starts three months before you turn 65

• Includes your birthday month

• Ends three months after you turn 65

During this time, you can sign up for Medicare Part A (hospital insurance) and Part B (medical insurance). If you want prescription drug coverage, you can also join a Part D plan.

If you sign up before your birthday month, coverage starts the first day of that month. If you sign up during or after, coverage may be delayed by one to three months.

What if You’re Still Working?

If you’re still working at 65 and have employer coverage, you may be able to delay Part B without penalty. But you must qualify for a Special Enrollment Period to avoid late fees later.

2. General Enrollment Period (GEP)

If you missed your IEP and don’t qualify for a Special Enrollment Period, you’ll need to wait for the General Enrollment Period (GEP).

• Runs from January 1 to March 31 each year

• Coverage begins July 1 of the same year

This applies mainly to people who didn’t sign up for Part B when first eligible and don’t have other coverage. Enrolling late can lead to a 10% Part B premium penalty for each full 12-month period you waited.

3. Special Enrollment Period (SEP)

Life isn’t always predictable, and Medicare understands that. The Special Enrollment Period (SEP) gives you flexibility when certain life events occur.

You may qualify for a SEP if:

• You lose employer health coverage

• You move out of your plan’s service area

• Your plan stops offering coverage

• You lose Medicaid eligibility

• You are released from incarceration

The timing and length of a SEP depend on the situation. Generally, you get two months after the qualifying event to make changes or enroll.

Employer Coverage SEP

If you delayed Medicare because you had qualifying employer coverage, you get an 8-month SEP to sign up for Part B after that coverage (or your job) ends.

• Coverage begins the first day of the month after you enroll

• No late penalty if you meet all the conditions

4. Medicare Advantage Open Enrollment Period

This window is only for those already enrolled in a Medicare Advantage (Part C) plan. It lets you make changes once a year:

• Runs from January 1 to March 31

• Switch to another Medicare Advantage plan or go back to Original Medicare

• Option to join a Part D plan if returning to Original Medicare

You can only make one change during this period. Any changes take effect the first day of the following month.

5. Annual Enrollment Period (AEP)

The Annual Enrollment Period (AEP) happens each fall and applies to most people with Medicare. You can:

• Join, drop, or switch Medicare Advantage plans

• Join, drop, or switch Part D drug plans

This enrollment window is:

• October 15 to December 7 every year

• Changes take effect January 1 of the following year

Even if you’re happy with your current coverage, it’s smart to review your plan each year. Costs and benefits can change.

6. Special Enrollment for Part B in 2024 (Now Closed)

In 2024, a one-time Special Enrollment Period for certain Postal retirees allowed enrollment in Medicare Part B without penalty. This SEP ended on September 30, 2024, and does not extend into 2025.

If you missed this window and are now subject to Part B penalties, you’ll need to wait until the next General Enrollment Period unless you qualify for a different SEP.

Penalties for Missing Deadlines

Late enrollment can carry long-lasting financial consequences. Here’s how:

• Part B Late Enrollment Penalty: 10% added to your premium for each full 12-month period you could’ve had Part B but didn’t. This penalty lasts as long as you have Part B.

• Part D Late Enrollment Penalty: Calculated as 1% of the national base premium multiplied by the number of months you were without coverage. This penalty also lasts indefinitely.

Avoiding penalties is one of the biggest reasons to keep a close eye on your enrollment timeline.

How to Enroll

You can sign up for Medicare through several methods, depending on what you’re applying for:

• Online at the Social Security website

• By phone with Social Security or Medicare

• In person at your local Social Security office

Enrollment for Part D or Medicare Advantage is typically done through the plan provider or through a licensed agent.

Staying on Top of Your Enrollment Timeline

Here’s a quick breakdown of the 2025 Medicare enrollment periods:

• Initial Enrollment Period (IEP): 7 months around your 65th birthday

• General Enrollment Period (GEP): Jan 1–Mar 31 (coverage begins July 1)

• Medicare Advantage Open Enrollment: Jan 1–Mar 31 (change once)

• Annual Enrollment Period (AEP): Oct 15–Dec 7 (changes take effect Jan 1)

• Special Enrollment Period (SEP): Triggered by qualifying life events (timing varies)

Using a calendar or reminder system can help you keep track. Missing even one deadline can create a ripple effect that leads to higher costs or delayed access to care.

What About Automatic Enrollment?

Some people are enrolled in Medicare automatically:

• If you’re receiving Social Security or Railroad Retirement Board benefits at least four months before you turn 65, you’re auto-enrolled in Part A and Part B.

• You’ll get your Medicare card in the mail three months before your 65th birthday.

If you’re not getting benefits yet, you need to sign up manually during your IEP.

The Importance of Reviewing Your Options

Medicare isn’t one-size-fits-all. Your health needs, budget, and current coverage can all influence your choices. As you approach an enrollment period, consider these questions:

• Are your prescriptions still covered under your current plan?

• Have your health conditions or needs changed?

• Is your doctor still in-network?

• Has your plan raised its premiums, copays, or deductibles?

Answering these can guide you toward better coverage and fewer surprises.

Enrollment Period Awareness Protects Your Benefits

Timing matters when it comes to Medicare. Whether you’re signing up for the first time or thinking about changing plans, the enrollment window you choose can shape your coverage, costs, and peace of mind.

Missing a deadline might mean penalties or going months without insurance. That’s why being proactive—and staying informed—is your best strategy.

If you’re unsure which enrollment period applies to your situation, speak with a licensed agent listed on this website to get the guidance you need.