Key Takeaways

• If you missed your Initial Enrollment Period (IEP), the General Enrollment Period (GEP) from January 1 to March 31 offers a second chance to enroll in Medicare Part A and/or Part B, but penalties may apply.

• Delaying enrollment could lead to permanent late penalties and coverage gaps. Understanding the timelines and eligibility criteria in 2025 helps you avoid these long-term costs.

What Happens If You Missed Your Initial Enrollment Period

Your Initial Enrollment Period (IEP) is the first window you’re given to sign up for Medicare. This 7-month period starts three months before the month you turn 65, includes your birthday month, and ends three months after. If you didn’t enroll during this time and you aren’t eligible for a Special Enrollment Period (SEP), you typically have to wait until the General Enrollment Period (GEP).

Missing the IEP isn’t rare—but it does carry consequences. You may face late enrollment penalties, and your Medicare coverage will be delayed. That’s where the General Enrollment Period becomes critical.

What Is the General Enrollment Period in 2025?

The General Enrollment Period runs every year from January 1 to March 31. If you missed your IEP and you’re not eligible for a Special Enrollment Period, this is your next opportunity to sign up for Medicare Part A and/or Part B.

Here’s what matters in 2025:

• If you enroll during the GEP, your coverage begins the first day of the month after you sign up. So if you enroll on February 10, your Medicare begins March 1.

• You can use this window only for Medicare Part A and Part B. This is not the time to enroll in Part C (Medicare Advantage) or Part D (prescription drug plans). You’ll get a separate opportunity for that.

How the General Enrollment Period Works

The GEP is for people who:

• Didn’t sign up during their IEP

• Aren’t eligible for a Special Enrollment Period (SEP)

• Don’t already have Medicare Part A or B

You can apply through:

• The Social Security Administration (SSA) website

• By phone through SSA

• By visiting a local SSA office (appointment recommended)

Once you enroll, you’ll be able to add drug coverage or switch to a Medicare Advantage plan during a separate window that begins on April 1.

Penalties Still Apply When You Enroll Late

The General Enrollment Period gives you a way to sign up—but not without costs. Medicare applies late enrollment penalties if you didn’t qualify for a Special Enrollment Period. These penalties are ongoing and can make your healthcare more expensive permanently.

Part B Late Enrollment Penalty

If you didn’t sign up for Part B during your IEP and weren’t covered by qualifying employer insurance, you’ll likely pay a late enrollment penalty.

• The penalty is 10% for each full 12-month period you delayed Part B enrollment.

• This amount is added to your monthly premium for as long as you have Part B.

Part A Late Enrollment Penalty

Most people don’t pay a premium for Part A. But if you do (because you haven’t worked enough quarters), and you missed enrolling on time:

• The penalty is 10% of the monthly premium.

• You’ll pay this for twice the number of years you delayed.

These penalties add up quickly and don’t go away unless you meet very specific exceptions.

Why Some People Miss the Initial Window

Many people assume Medicare enrollment is automatic at 65, but that’s not always true.

You must actively enroll if:

• You’re not receiving Social Security or Railroad Retirement Board benefits at 65

• You’re still working and delaying retirement

If you delay Medicare without creditable employer coverage, you risk penalties. Some assume retirement coverage will protect them—but retiree plans, COBRA, and ACA marketplace plans do not count as creditable coverage for Medicare Part B.

You May Still Qualify for a Special Enrollment Period (SEP)

Before jumping into the General Enrollment Period, confirm whether you might qualify for a Special Enrollment Period (SEP). This option lets you avoid penalties and delays.

You may qualify for an SEP if:

• You lost employer coverage recently

• You moved out of your plan’s service area

• You were released from incarceration

• You gained lawful presence in the U.S.

SEPs come with specific timelines and documentation requirements. If you’re unsure whether you qualify, talk to a licensed agent listed on this website or reach out to Social Security directly.

When Can You Get Full Medicare Coverage After GEP Enrollment?

Enrolling in Part A and/or Part B during the GEP is only part of the process. Once you’ve done that, you can get full Medicare coverage by adding:

• Part D (Prescription Drug Coverage): After signing up for Part B, you can enroll in a drug plan between April 1 and June 30.

• Medicare Advantage (Part C): You can also join a Medicare Advantage plan during that same April 1 to June 30 window, as long as you’ve enrolled in both Part A and Part B.

Note: If you delay adding drug coverage beyond this window, you could face additional late enrollment penalties under Part D rules.

Coordinating Medicare With Other Coverage

If you’re enrolling during the GEP, it’s important to think about how Medicare will work with any other coverage you may have—or may want to drop.

• Employer Insurance: If you’re over 65 and your employer coverage has ended or you’re no longer working, Medicare becomes your primary insurance.

• Retiree Coverage or COBRA: These don’t count as creditable coverage for delaying Medicare Part B. Enroll in Medicare first, or you may risk both gaps and penalties.

Avoiding Common Mistakes During the GEP

To make the most of this second chance, keep these common missteps in mind:

• Waiting too long within the GEP window: The later you enroll, the later your coverage begins. This increases your risk of having no coverage during a critical period.

• Assuming penalties won’t apply: Late enrollment penalties are automatically calculated based on your timeline.

• Not preparing for next steps: Signing up for Part A and B is not the end. Be ready to act during the April–June window to add drug coverage or switch to a Medicare Advantage plan.

• Forgetting IRMAA: If your income is above a certain threshold, you may owe an additional amount for Part B and D premiums. This Income-Related Monthly Adjustment Amount (IRMAA) is determined by your IRS-reported income from two years prior.

Important 2025 Dates to Remember

• January 1 – March 31: General Enrollment Period for Medicare Part A and B

• April 1 – June 30: Medicare Advantage and Part D enrollment for those who enrolled during GEP

• October 15 – December 7: Annual Enrollment Period (for changing coverage for the next year)

Mark your calendar with these dates so you can act without delay. Missing any of these timeframes could leave you with fewer options—or higher costs.

What To Do If You’re Not Sure About Your Options

Medicare can be complex—especially if you’re already late. If you’re uncertain whether the GEP applies to you or whether you qualify for an SEP instead, it’s wise to get help.

A licensed agent listed on this website can walk you through:

• Whether penalties apply in your situation

• Which coverage options best match your needs

• How to prepare for the next enrollment window

• Whether you qualify for cost-saving programs like Extra Help or Medicaid

Getting expert support ensures you’re not making costly assumptions or delays.

A Late Start Doesn’t Mean You’re Out of Options

If you waited too long to sign up for Medicare, the General Enrollment Period gives you a chance to catch up. But you must act quickly and carefully. The rules are strict, the penalties can last a lifetime, and timing matters more than ever.

To make sure you choose the right path, contact a licensed agent listed on this website. They can help you understand your rights, your deadlines, and your options moving forward in 2025.