Medicare Enrollment Periods Explained: Everything You Need to Know

Medicare Part A & Part B Enrollment Periods

1. Initial Enrollment Period (IEP)

Your Initial Enrollment Period is your first opportunity to sign up for Medicare Parts A and B. This period lasts for seven months, starting three months before the month you turn 65, including your birthday month, and continuing for three months after.

If you sign up before your birthday month, your Medicare coverage begins on the first day of your birth month. If you enroll during or after your birthday month, your coverage may be delayed.

2. Special Enrollment Period (SEP) for Employer Coverage

If you’re still working at 65 and have employer health coverage, you may delay Medicare enrollment without penalties. When you retire or lose employer coverage, you’ll get an eight-month Special Enrollment Period to sign up for Medicare Part B without a penalty.

However, most people enroll immediately when leaving employer coverage to avoid gaps in healthcare.

3. General Enrollment Period (GEP)

If you miss your Initial Enrollment Period and don’t qualify for a Special Enrollment Period, you can enroll in Medicare during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage will start on July 1, and you may face late penalties.

Medicare Supplement, Medicare Advantage, and Drug Plan Enrollment Periods

1. Medicare Supplement (Medigap) Open Enrollment Period

Medicare Supplement Plans (Medigap) help cover out-of-pocket costs like copays and deductibles. You have a six-month open enrollment period starting on the first day of the month you are 65 and enrolled in Medicare Part B.

During this period, you can enroll in a Medigap plan without health questions or medical underwriting. Outside of this window, you may be subject to medical underwriting and could be denied coverage.

2. Medicare Advantage & Part D Initial Enrollment Period

If you want a Medicare Advantage (Part C) or Part D (prescription drug) plan, you can enroll during your seven-month Initial Enrollment Period (IEP), the same period as signing up for Parts A and B.

3. Annual Enrollment Period (AEP) – October 15 to December 7

During the Annual Enrollment Period (AEP), you can:

• Switch from Original Medicare to Medicare Advantage (or vice versa)
• Change from one Medicare Advantage plan to another
• Enroll in, change, or drop a Part D drug plan

Changes made during this period take effect on January 1 of the following year.

4. Medicare Advantage Open Enrollment Period (OEP) – January 1 to March 31

If you’re already enrolled in a Medicare Advantage plan, this period allows you to:

• Switch to another Medicare Advantage plan
• Drop your Medicare Advantage plan and return to Original Medicare

However, you cannot switch from Original Medicare to Medicare Advantage during this period.

Special Enrollment Periods (SEPs) for Medicare Advantage & Part D

Certain life events qualify you for a Special Enrollment Period (SEP) outside of standard enrollment windows. The most common SEPs include:

• Moving: If you move out of your plan’s service area, you can switch to a new plan.
• Losing Employer Coverage: If you lose employer or union coverage, you qualify for a SEP to enroll in a Medicare Advantage or Part D plan.
• Medicare Plan Termination: If your Medicare plan is discontinued, you qualify for a SEP to choose a new plan.
• Qualifying for Medicaid or Extra Help: If you gain or lose eligibility for Medicaid or Extra Help, you can switch plans.

Avoiding Medicare Late Enrollment Penalties

Failing to enroll in Medicare Part B when you’re first eligible can result in a lifetime penalty, increasing your Part B premium by 10% for each full 12-month period you were eligible but didn’t enroll. Similarly, Part D late enrollment penalties apply if you go 63 consecutive days or more without prescription drug coverage after your Initial Enrollment Period.

Need Help with Medicare Enrollment?

Understanding Medicare enrollment periods can be confusing, but missing a deadline could mean higher costs or limited coverage options. If you have questions or need personalized guidance, give us a call at 800-208-4974. We’re happy to help you find the right Medicare coverage for your needs.