Medicare Enrollment Windows: When Can You Sign Up or Switch Plans?

One of the biggest mistakes seniors make with Medicare is missing an enrollment deadline. The consequences can be serious: a permanent late enrollment penalty, a gap in coverage, or being stuck in a plan that doesn't fit your needs for an entire year.

The good news? Once you understand the enrollment windows, they're not complicated. Here's everything you need to know.

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1. Initial Enrollment Period (IEP)

Your Initial Enrollment Period is the first opportunity you have to sign up for Medicare. It's a 7-month window that includes:

• The 3 months before your 65th birthday month
• Your birthday month itself
• The 3 months after your birthday month

Example: If your birthday is June 15, your IEP runs from March 1 through September 30.

Why the Timing Matters

When you enroll during your IEP affects when your coverage starts:

• Enroll in the 3 months before your birthday → coverage starts on your birthday month
• Enroll during your birthday month → coverage starts the following month
• Enroll in the 3 months after → coverage is delayed by 1–3 months

Pro tip: Enroll in the 3 months before your birthday to avoid any gap in coverage.

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2. Annual Enrollment Period (AEP)

The Annual Enrollment Period runs every year from October 15 through December 7. This is when anyone already on Medicare can:

• Switch from Original Medicare to a Medicare Advantage plan
• Switch from one Medicare Advantage plan to another
• Switch from Medicare Advantage back to Original Medicare
• Join, switch, or drop a Part D prescription drug plan

Changes made during AEP take effect January 1 of the following year.

Should You Review Your Plan Every Year?

Yes — absolutely. Insurance companies can change their plans every year, including:

• Premiums and deductibles
• Which drugs are covered (formulary changes)
• Which doctors and hospitals are in-network
• Extra benefits like dental and vision

A plan that was perfect last year might not be the best fit this year. I recommend reviewing your plan every October.

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3. Medicare Advantage Open Enrollment Period (MA OEP)

From January 1 through March 31, if you're already enrolled in a Medicare Advantage plan, you can:

• Switch to a different Medicare Advantage plan
• Drop your Medicare Advantage plan and return to Original Medicare (and enroll in a Part D plan)

You can only make one change during this period, and it takes effect the first day of the month after you enroll.

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4. Special Enrollment Periods (SEPs)

Life happens. Special Enrollment Periods allow you to make changes to your Medicare coverage outside of the standard enrollment windows when certain qualifying events occur.

Common qualifying events include:

• Losing employer or union coverage (you or your spouse retires)
• Moving to a new address that's outside your current plan's service area
• Moving into or out of a nursing home or assisted living facility
• Your plan leaves Medicare or stops covering your area
• Qualifying for Extra Help (Low Income Subsidy) for Part D costs
• Becoming eligible for Medicaid

SEPs are typically 2 months from the qualifying event, though some are longer.

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5. General Enrollment Period (GEP)

If you missed your Initial Enrollment Period and don't qualify for a Special Enrollment Period, you can sign up during the General Enrollment Period: January 1 through March 31 each year.

Coverage begins July 1 of that year.

Important: If you enroll during the GEP, you may face a late enrollment penalty for Part B — an additional 10% added to your premium for every 12-month period you were eligible but didn't enroll. This penalty is permanent.

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The Late Enrollment Penalty: What You Need to Know

Missing your enrollment window can cost you — permanently.

Part B Late Penalty

For every 12-month period you were eligible for Part B but didn't enroll, your premium increases by 10%. If you waited 2 years, that's a 20% permanent increase.

Part D Late Penalty

For every month you go without creditable prescription drug coverage after becoming eligible, you'll pay 1% of the national base beneficiary premium added to your monthly Part D premium — permanently.

Exception: If you had creditable drug coverage through an employer or union plan, you won't face a penalty as long as you enroll within 63 days of losing that coverage.

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What If You Missed a Deadline?

Don't panic — but do act quickly. Here's what to do:

1. Determine if you qualify for a Special Enrollment Period. Many people don't realize they qualify for an SEP based on their situation.
2. Check if you have creditable coverage through an employer, union, or other source that may protect you from penalties.
3. Talk to a licensed Medicare broker who can review your specific situation and help you find the best path forward.

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Get Help Before the Deadline

Enrollment windows can feel overwhelming, but you don't have to navigate them alone. At JWB Insurance Group, we help seniors in Houston and across Texas understand their options and enroll in the right plan at the right time — in English or Spanish.

Call us at (281) 743-8691 or visit our contact page to schedule a free consultation before your next enrollment window closes.

— Jorge W. Barrientos, Licensed Medicare Insurance Broker

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JWB Insurance Group LLC is a licensed independent insurance agency. We are not affiliated with or endorsed by the U.S. government or the federal Medicare program.