Understanding Medicare Enrollment Periods

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Your Guide to Medicare Enrollment, Important Deadlines, and When You Can Make Changes

Medicare can be confusing, especially when it comes to knowing when you can enroll, switch plans, or make changes to your coverage.

Whether you're turning 65, retiring, losing employer coverage, or simply looking for better Medicare benefits, understanding your enrollment periods is an important first step.

At The Dean Agency, our independent Medicare insurance specialists help individuals and families throughout Dearborn, Detroit, and Southeast Michigan navigate Medicare enrollment with confidence.

There are several Medicare enrollment periods, and each serves a different purpose. Here's what you need to know.

When: The seven-month period surrounding your 65th birthday.

For most people, their first opportunity to enroll in Medicare begins three months before the month they turn 65 and ends three months afterward.

For example, if you turn 65 in July:

• April, May, and June — The three months before your birthday month
• July — Your birthday month
• August, September, and October — The three months afterward

During this period, you can generally enroll in Medicare Part A (hospital insurance) and Medicare Part B (medical insurance). Once eligible, you can also choose Medicare Advantage or prescription drug coverage.

Our recommendation: Begin reviewing your Medicare options at least three months before turning 65.

Enrolling early helps avoid unnecessary gaps in coverage and provides time to compare Medicare with any employer-sponsored insurance you may have.

Important: If your birthday falls on the first day of the month, Medicare uses slightly different timing rules. Some people are also automatically enrolled in Medicare.

When: October 15 through December 7, every year.

Medicare's Annual Enrollment Period, also called Medicare Open Enrollment, is the primary opportunity for people with Medicare to review their existing coverage and make changes for the following year.

For 2027 Medicare coverage, AEP runs October 15 through December 7, 2026.

During AEP, eligible beneficiaries can:

• Switch from one Medicare Advantage plan to another.
• Change from Original Medicare to a Medicare Advantage plan.
• Leave Medicare Advantage and return to Original Medicare.
• Join, switch, or drop a Medicare Part D prescription drug plan, subject to applicable rules.

Changes made during this period generally become effective January 1 of the following year.

Even if you're satisfied with your current coverage, insurance companies can change their benefits, costs, provider networks, pharmacy networks, and prescription drug formularies from one year to the next.

A plan that worked well this year may not be the best fit next year.

At The Dean Agency, our annual Medicare reviews focus on:

• Your doctors: Are your preferred healthcare providers participating in the plan's network?
• Your medications: Are your prescriptions covered, and have their costs or restrictions changed?
• Your benefits: Do the plan's available benefits align with your healthcare needs?
• Your expenses: What can you expect to pay in premiums, copayments, deductibles, and other out-of-pocket costs?

You do not necessarily need to change plans every year. Sometimes, keeping your current coverage is the right decision.

Our goal is to help you make an informed choice.

When: January 1 through March 31, every year.

The Medicare Advantage Open Enrollment Period is an additional opportunity for people already enrolled in a Medicare Advantage plan to make one qualifying change.

During this period, you can:

• Switch to another Medicare Advantage plan, with or without prescription drug coverage.
• Leave Medicare Advantage and return to Original Medicare.
• Enroll in a separate Part D prescription drug plan if you return to Original Medicare.

Changes generally take effect on the first day of the month after your new plan receives your enrollment request.

If you have Original Medicare, this period does not allow you to enroll in Medicare Advantage for the first time.

It also does not generally allow individuals with Original Medicare to switch between standalone Part D prescription drug plans.

There is a separate Medicare Advantage enrollment opportunity for certain beneficiaries during their first three months with Medicare.

Not every Medicare enrollment period is available to everyone. Understanding which rules apply to your situation is essential.

When: Varies depending on your qualifying circumstances.

Many people believe they can only change Medicare coverage between October 15 and December 7.

Fortunately, that isn't always the case.

Certain life events and changes in eligibility may qualify you for a Special Enrollment Period, allowing you to enroll in or change Medicare coverage outside the usual enrollment windows.

Common situations include:

Moving to a new location

If you move outside your Medicare plan's service area, or to a location with new plan options, you may qualify for an enrollment opportunity.

Losing qualifying health coverage

Losing certain employer, union, or other health coverage may create additional enrollment rights.

Qualifying for Medicaid or Extra Help

Individuals who receive Medicaid or Medicare's Extra Help program may qualify for additional opportunities to change prescription drug or qualifying Medicare coverage.

Changes in your Medicare plan

If your plan terminates its Medicare contract, stops serving your area, or certain other changes occur, you may qualify for a Special Enrollment Period.

Michigan residents who qualify for both Medicare and Medicaid may have additional coverage options through Dual Eligible Special Needs Plans (D-SNPs).

Certain beneficiaries can use special enrollment opportunities to coordinate Medicare and Medicaid benefits through qualifying integrated plans.

The availability of these opportunities depends on your eligibility, plan type, and other Medicare requirements.

Our team can help explain which enrollment periods and coverage options may apply to your circumstances.

When: January 1 through March 31, every year.

The General Enrollment Period is primarily intended for people who missed their opportunity to enroll in Medicare Part B (or premium Part A) and do not qualify for a Special Enrollment Period.

If you enroll during the General Enrollment Period, your Medicare coverage generally begins the following month.

However, you may face a late enrollment penalty if you delayed Medicare enrollment without qualifying coverage or another exception.

Important distinction: The General Enrollment Period is for enrolling in Original Medicare Part A and/or Part B. It is different from the Medicare Advantage Open Enrollment Period, even though both occur between January and March.

When: Generally while covered by qualifying current-employment group health insurance, or within eight months after the employment or coverage ends, whichever happens first.

Many people continue working beyond age 65 and choose to delay Medicare Part B because they have health insurance through their employer or their spouse's employer.

Depending on their situation, they may qualify for a Special Enrollment Period that allows them to enroll in Part B without a late enrollment penalty.

However, the rules depend on the type of coverage you have.

COBRA and retiree health insurance generally do not extend the eight-month Medicare Part B Special Enrollment Period.

It's also important to understand how Medicare coordinates with employer insurance, particularly when working for a smaller employer.

Before retiring or dropping employer coverage, we encourage you to compare your current benefits with your available Medicare options.

Medicare Supplement insurance, also called Medigap, follows different enrollment rules from Medicare Advantage.

Your federal Medigap Open Enrollment Period generally lasts six months, beginning the first month you are both age 65 or older and enrolled in Medicare Part B.

During this period, you have important protections when purchasing Medigap coverage.

Outside your Medigap Open Enrollment Period or another guaranteed-issue situation, an insurance company may be permitted to use medical underwriting to determine eligibility or pricing.

This is why choosing between Medicare Advantage and Medicare Supplement coverage deserves careful consideration.

The October 15–December 7 Annual Enrollment Period does not automatically give everyone the right to purchase a Medigap policy without medical underwriting.

Generally, no. Most Medicare Advantage and prescription drug plan changes must occur during a qualifying enrollment period. Certain life events may allow you to make changes at other times.

Usually not. If your current Medicare coverage continues into the following year, it will generally renew automatically unless you make a change. However, your benefits and costs may change, and some plans may no longer be offered.

If you miss the December 7 deadline, you may need to wait until another enrollment period. Individuals already enrolled in Medicare Advantage may have an opportunity to make one change during the Medicare Advantage Open Enrollment Period from January 1 through March 31. Special Enrollment Periods may also apply.

Yes. Certain people qualify for Medicare before age 65 because of a disability, End-Stage Renal Disease (ESRD), or Amyotrophic Lateral Sclerosis (ALS). Eligibility and enrollment rules vary.

Possibly. If you have qualifying health coverage through your or your spouse's current employment, you may be able to delay Part B without a penalty. The employer's size, type of coverage, and other circumstances can affect that decision.

You might. Medicare Part B and Part D have different late enrollment penalty rules. Part D penalties may apply if you go 63 consecutive days or more without Medicare drug coverage or other creditable prescription drug coverage after your initial enrollment opportunity. Certain exceptions apply.

There is no cost to use The Dean Agency's Medicare insurance assistance services, and there is no obligation to enroll.

Medicare enrollment is more than selecting an insurance plan. It's about understanding how your coverage works with your doctors, prescriptions, healthcare needs, and financial situation.

The Dean Agency is an independent Medicare insurance agency founded by Shadi Shamsedean, Doctor of Pharmacy (PharmD).

Our healthcare-focused approach combines knowledge of prescription medications and insurance coverage with personalized Medicare guidance.

We proudly assist individuals throughout Dearborn, Detroit, Wayne County, Oakland County, Macomb County, Washtenaw County, and surrounding Michigan communities.

Whether you're turning 65, reviewing your Medicare coverage, exploring Medicare Advantage or Medigap, or navigating Medicare and Medicaid eligibility, we're here to help.

You don't have to navigate Medicare alone.

Contact The Dean Agency today for personalized guidance and a no-obligation Medicare coverage review.

The Dean Agency — Trusted Medicare Specialists

Independent Medicare Insurance Guidance | Dearborn, Michigan

Educational information only. Enrollment eligibility, timing, and coverage options depend on individual circumstances. Medicare rules and plan availability are subject to change.

Last updated: October 2026