When is my Initial Enrollment Period for Medicare?

Your Initial Enrollment Period is a seven-month window. It starts 3 months before the month you turn 65, includes your birthday month, and runs 3 months after.

When does my Medicare coverage start?

If you enroll in the 3 months before your birthday month, coverage begins the first day of your birthday month. If you enroll during your birthday month or in the 3 months after, coverage begins the first day of the following month.

What happens if I miss my Initial Enrollment Period?

You can sign up during the General Enrollment Period, January 1 to March 31, with coverage beginning the first day of the month after you enroll. A Part B late enrollment penalty of 10% for each full 12-month period you were eligible but not enrolled applies for as long as you have Part B.

What is the Medicare Advantage Open Enrollment Period?

From January 1 to March 31, if you are already in a Medicare Advantage plan, you can switch to a different Advantage plan, return to Original Medicare, or add or drop a Part D plan. You cannot use this window to join Medicare Advantage for the first time.

When can I buy a Medicare Supplement without medical underwriting?

During your Medigap Open Enrollment Period, a six-month window beginning the first month you are both 65 and enrolled in Part B. After it closes, most states allow insurers to deny you or charge more based on health history.

Does COBRA give me a Special Enrollment Period for Part B?

No. COBRA is not coverage based on current employment. The eight-month Part B Special Enrollment Period starts when your active employment or employer coverage ends, not when COBRA runs out.

Medicare Enrollment Periods

Q: What can I change during the Annual Enrollment Period?

From October 15 to December 7 you can move between Original Medicare and Medicare Advantage in either direction, switch Medicare Advantage plans, or enroll in, cancel, or change a Part D plan. Changes take effect January 1.

Medicare has five enrollment windows: your Initial Enrollment Period when you first become eligible, the General Enrollment Period if you miss it, the Annual Enrollment Period each fall, the Medicare Advantage Open Enrollment Period each winter, and Special Enrollment Periods triggered by specific life events. Each one allows different changes, and using the wrong one, or missing one entirely, can cost you money or coverage. When you first enroll in Medicare during your Initial Enrollment Period, you select Original Medicare (Parts A and B) or a Medicare Advantage plan (Part C), which combines the two types of coverage. Part D prescription drug coverage is also available with either option. Once you make your selection, you are not stuck with it for life. Medicare gives you several opportunities to change your plan depending on your situation.

Your Initial Enrollment Period (IEP)

Your Initial Enrollment Period is a seven-month window built around your 65th birthday. It starts 3 months before the month you turn 65, includes your birthday month, and runs 3 months after. This is when most people sign up for Parts A and B. See our getting started guide for the full walkthrough. When your coverage begins depends on when in that window you enroll:

The 3 months before your birthday month: coverage begins the first day of your birthday month
Your birthday month: coverage begins the first day of the following month
The 3 months after your birthday month: coverage begins the first day of the month after you enroll

That last rule changed as of January 2023. Before then, enrolling late in your IEP could push your start date back by up to three months. That no longer happens, but waiting still costs you weeks or months of coverage you could have had. If your birthday falls on the 1st of the month, Medicare treats you as turning 65 the month before, so your entire seven-month window shifts one month earlier. Miss this window without qualifying employer coverage and you face a Part B late enrollment penalty of 10% for every full 12-month period you were eligible but not enrolled, added to your premium for as long as you have Part B.

The General Enrollment Period (GEP)

From January 1 to March 31 each year, if you missed your Initial Enrollment Period and do not qualify for a Special Enrollment Period, you can still sign up for Part B. Your coverage begins the first day of the month after you enroll. This rule also changed in January 2023. Coverage used to start July 1 regardless of when you enrolled, which could leave people uninsured for months. That delay is gone, but the late enrollment penalty still applies.

Medicare’s Annual Enrollment Period (AEP)

From October 15 to December 7 each year, you can change your Part C or Part D coverage during the Annual Enrollment Period. This is the widest window: you can move between Original Medicare and Medicare Advantage in either direction, switch Medicare Advantage plans, or enroll in, cancel, or change a Part D plan. Changes you make take effect January 1. See our full AEP breakdown for the complete rules and deadlines. At this time, you can:

Change from Original Medicare to a Medicare Advantage plan
Drop a Medicare Advantage plan and go back to Original Medicare
Change from one Medicare Advantage plan to a different one
Enroll in a Part D prescription drug plan
Cancel your Part D prescription drug plan
Change your Part D prescription drug plan

Medicare Advantage Open Enrollment Period

From January 1 to March 31 each year, if you are already enrolled in a Medicare Advantage plan, you get one chance to switch to a different Medicare Advantage plan, drop it and return to Original Medicare, or add or drop a Part D plan. You cannot use this window to join Medicare Advantage for the first time from Original Medicare. See our full OEP guide for details on what you can and cannot do. During this time you can:

Switch from one Medicare Advantage plan to another
Drop Medicare Advantage and return to Original (Parts A and B) Medicare
Add a Part D prescription plan
Drop a Part D prescription plan

Yes, you can drop a Medicare Advantage plan and return to Original Medicare, but do not count on a Medigap plan if that is your intention. Medigap carriers can medically underwrite and decline you outside specific guaranteed-issue situations.

The Medigap Window Most People Miss

Separate from all of the above, you have a one-time Medigap Open Enrollment Period. It is six months long and begins the first month you are both 65 and enrolled in Part B. During it, no insurer can deny you a Medicare Supplement or charge you more because of your health history. Once that window closes, most states allow medical underwriting on Medigap applications. This is why choosing Medicare Advantage at 65 can be difficult to reverse later: the Advantage plan can be dropped during OEP or AEP, but the Medigap policy you want to replace it with may not accept you.

What If You Need to Make Changes Outside These Windows?

In certain situations, such as a move or loss of coverage, you may qualify for a Special Enrollment Period (SEP) to make changes to your Medicare plan outside AEP or OEP. Most SEPs run two months, though the window tied to losing coverage based on current employment is eight months for Part B. For example, moving from one service area to another may qualify you for an SEP if your current plan’s network is not available at your new address. During your SEP, you can switch to a new Medicare Advantage or Part D plan, or return to Original Medicare, without penalty. In some situations, you may also be able to enroll in a Medigap plan without medical underwriting. This is called a guaranteed-issue right. One important distinction: COBRA and retiree coverage are not coverage based on current employment, so neither one triggers the eight-month Part B window. That clock starts when your active employment or employer coverage ends, not when COBRA runs out. If you believe you may qualify for a Special Enrollment Period, contact your plan administrator as soon as possible after the qualifying event. We can help you determine whether you qualify and walk you through the process. Questions about which window applies to you? Call Scott Bowling directly at 512-844-3983, or pick a time and I’ll call you.