Medicare Enrollment Periods
Medicare has specific windows when you can enroll, switch plans, or make changes to your coverage. Missing a deadline can mean penalties or gaps in coverage. Here's what you need to know.
Why Enrollment Timing Matters
Unlike most health insurance, you cannot simply sign up for Medicare whenever you want. The federal government has established specific enrollment periods that determine when you can enroll in Medicare for the first time, when you can switch plans, and when you can add or change coverage.
Understanding these windows is critical. Enrolling late can result in lifelong premium penalties, and missing your window means waiting until the next eligible period — potentially leaving you without coverage for months. Below, we explain each enrollment period in detail.
Initial Enrollment Period (IEP)
For people turning 65 or first becoming eligible
Your Initial Enrollment Period is the first opportunity to enroll in Medicare. It is a 7-month window that surrounds your 65th birthday (or your 25th month of receiving SSDI benefits):
What You Can Do During Your IEP
- Sign up for Medicare Part A and/or Part B
- Enroll in a Medicare Advantage (Part C) plan
- Enroll in a standalone Part D prescription drug plan
- Purchase a Medicare Supplement (Medigap) plan during your guaranteed-issue Medigap Open Enrollment Period
When Coverage Starts
If you enroll during the first three months of your IEP (before your birthday month), your coverage typically begins on the first day of your birthday month. Enrolling later in the IEP delays your coverage start date by one to three months. For the earliest possible start, enroll as soon as your IEP opens.
Annual Enrollment Period (AEP)
October 15 – December 7 each year
The Annual Enrollment Period (also called the Fall Open Enrollment) is the main yearly window when all Medicare beneficiaries can review their coverage and make changes. It runs from October 15 through December 7, with changes taking effect on January 1 of the following year.
What You Can Do During the AEP
- Switch from one Medicare Advantage plan to another
- Switch from Original Medicare to a Medicare Advantage plan
- Switch from a Medicare Advantage plan back to Original Medicare (and add a Medigap plan, subject to underwriting)
- Join a Medicare Part D prescription drug plan
- Switch from one Part D plan to another
- Drop your Part D coverage
Why Annual Reviews Matter
Medicare plans can change their benefits, costs, drug formularies, and provider networks every year. A plan that worked well for you this year may not be the best option next year. We recommend reviewing your coverage with an agent every fall to ensure your plan still meets your needs and that you are not overpaying.
Pro Tip
Insurance carriers release their plan details for the following year on October 1 — two weeks before the AEP opens. This gives you time to review upcoming changes and be ready to act when enrollment opens on October 15.
Medicare Advantage Open Enrollment Period (OEP)
January 1 – March 31 each year
The Medicare Advantage Open Enrollment Period gives people who are already in a Medicare Advantage plan one additional opportunity to make a change at the beginning of the year. It runs from January 1 through March 31, with changes taking effect the first of the month after the plan receives your enrollment request.
What You Can Do During the OEP
- Switch from one Medicare Advantage plan to another Medicare Advantage plan
- Drop your Medicare Advantage plan and return to Original Medicare
- If you return to Original Medicare, you can also join a standalone Part D plan
Important Limitations
The OEP is only available to people who are currently enrolled in a Medicare Advantage plan. If you are on Original Medicare and want to join a Medicare Advantage plan, you must wait for the Annual Enrollment Period (or qualify for a Special Enrollment Period). You can only make one plan change during the OEP.
Special Enrollment Periods (SEP)
Available when qualifying life events occur
Special Enrollment Periods allow you to make changes to your Medicare coverage outside of the standard enrollment windows. SEPs are triggered by specific qualifying life events. Here are the most common:
- You move out of your plan's service area. If you relocate to an area where your current plan is not available, you qualify for a SEP to choose a new plan.
- You lose employer or union coverage. When you retire or lose employer-sponsored health insurance, you get an 8-month SEP to enroll in Part B and choose Medicare coverage without penalty.
- You qualify for Medicaid or Extra Help. If you become eligible for Medicaid or the Medicare Part D Extra Help (Low Income Subsidy) program, you receive a SEP to enroll in or switch plans.
- You are in a nursing home or long-term care facility. Residents of skilled nursing facilities or similar institutions have a continuous SEP to change plans at any time.
- Your plan leaves Medicare or reduces service area. If your plan terminates its Medicare contract or stops serving your area, you qualify for a SEP.
- You experience other qualifying events. Additional SEPs exist for situations like being released from incarceration, losing coverage through no fault of your own, or experiencing a natural disaster in your area.
SEP rules can be complex, and eligibility varies by situation. Our agents can help determine whether you qualify for a Special Enrollment Period and guide you through the process.
General Enrollment Period (GEP)
If you missed your Initial Enrollment Period and do not qualify for a Special Enrollment Period, the General Enrollment Period is your fallback option. It runs from January 1 through March 31 each year, with coverage starting on July 1.
What You Can Do During the GEP
- Sign up for Medicare Part A (if you did not enroll when first eligible)
- Sign up for Medicare Part B (if you did not enroll when first eligible)
Late Enrollment Penalties
Enrolling during the GEP typically means you will pay a late enrollment penalty. For Part B, your premium increases by 10% for each full 12-month period you could have been enrolled but were not. This penalty is added to your Part B premium for as long as you have Medicare. This is why it is so important to enroll on time or ensure you have qualifying employer coverage that allows you to delay without penalty.
Medigap Open Enrollment Period
The Medigap Open Enrollment Period is a one-time, 6-month window that begins when you are both 65 or older and enrolled in Medicare Part B. During this period:
- You have a guaranteed right to purchase any Medigap plan sold in your state, regardless of your health status.
- Insurance companies cannot deny you coverage or charge you higher premiums due to pre-existing conditions.
- This is the best time to buy a Medigap plan if you choose the Original Medicare path.
After this 6-month window closes, you may still be able to buy a Medigap plan, but insurance companies can use medical underwriting. They may charge you more or deny you coverage based on your health history. This makes the Medigap Open Enrollment Period one of the most important windows in your Medicare journey.
Quick Reference Guide
Initial Enrollment Period (IEP)
When: 7 months around your 65th birthday
Who: People first becoming eligible for Medicare
Annual Enrollment Period (AEP)
When: October 15 - December 7
Who: All Medicare beneficiaries
Open Enrollment Period (OEP)
When: January 1 - March 31
Who: People currently in a Medicare Advantage plan
Special Enrollment Period (SEP)
When: Varies by qualifying event
Who: People experiencing qualifying life changes
General Enrollment Period (GEP)
When: January 1 - March 31 (coverage starts July 1)
Who: People who missed their IEP
Medigap Open Enrollment
When: 6 months starting when you turn 65 and have Part B
Who: People choosing Original Medicare + Medigap
Don't Miss Your Enrollment Window
Our licensed agents will identify the right enrollment period for your situation and ensure you meet every deadline — at no cost to you.