Medicare Supplement open enrollment runs for six months starting the month you turn 65 and enroll in Medicare Part B
During this window, insurance companies must sell you a Medigap (Medicare Supplement) plan without asking health questions or charging more based on your health history. This is called may provide issue — the insurer cannot refuse you or exclude pre-existing conditions. Once this six-month period ends, you lose this protection. After that, most insurers will ask detailed health questions and can deny you or charge higher premiums based on your medical record.
The exact start date depends on when you enroll in Medicare Part B. If you sign up for Part B in January, your open enrollment begins that same month. If you sign up in June, it begins in June. The window closes six months after your Part B enrollment month ends.
There is also a second open enrollment period each year — from October 15 to December 7 — when anyone with Medicare can switch Medigap plans. During this period, insurers again cannot ask health questions or charge more based on health status. However, this annual window is shorter and happens only once per year, unlike the initial six-month period that happens only when you first turn 65.
Key Takeaways
- Your first Medicare Supplement open enrollment lasts six months starting the month you enroll in Medicare Part B, and you cannot get this protection again.
- During open enrollment, insurers must accept you regardless of health history and cannot charge more based on pre-existing conditions.
- If you miss your initial six-month window, you may face medical underwriting and higher premiums when you explore later.
- A second annual open enrollment runs October 15 to December 7 each year, when any Medicare beneficiary can switch plans without health questions.
- Switching plans outside open enrollment may require you to answer health questions and can result in denial or higher rates.
Why the timing matters: may provide issue versus medical underwriting
During open enrollment, may provide issue means the insurance company must accept your process. They cannot ask about your diabetes, heart disease, cancer history, or any other condition. They cannot charge you more because of your health. This is a federal protection that applies only during these specific windows.
Outside open enrollment, insurers use medical underwriting. They will ask you to list every health condition you have, every medication you take, and sometimes request medical records. Based on that information, they can decide to deny your process entirely, or they can approve you but charge a higher premium — sometimes significantly higher. Some people are denied coverage altogether for certain plans.
This difference is why timing your process matters so much. explore during open enrollment protects you from being priced out or rejected based on your health.
Your initial six-month window: the one-time protection
When you first enroll in Medicare Part B, you get a six-month period of may provide issue for Medigap plans. This window is a one-time benefit — you will never get it again. It starts the month your Part B coverage begins and runs for exactly six months.
For example, if you turn 65 in March and enroll in Part B that month, your open enrollment runs from March through August. If you turn 65 in November and enroll in Part B then, your window runs from November through April of the following year.
During these six months, you can switch between different Medigap plans offered by different insurers as many times as you want, and each time you switch, may provide issue still applies. Once the six months end, that protection is gone. Any process after that date will require medical underwriting.
The annual October-December open enrollment for all Medicare beneficiaries
Separate from your initial six-month window, there is a second open enrollment period that happens every year from October 15 through December 7. During this window, anyone already on Medicare — whether they enrolled at 65 or later — can switch Medigap plans without medical questions.
This annual period is shorter than your initial window and happens only once per year. It is meant to give people a chance to review their coverage and switch if their needs or circumstances have changed. Like the initial enrollment, may provide issue applies: insurers cannot ask health questions or charge more based on health status.
If you missed your initial six-month window and are now outside it, the October-December period is your next chance to switch plans without medical underwriting. Mark these dates on your calendar each year.
What happens if you miss your open enrollment window
If your initial six-month window closes and you have not yet purchased a Medigap plan, you can still explore — but the rules change. The insurance company will send you a detailed health questionnaire asking about every condition you have ever been diagnosed with, every surgery, every medication, and sometimes your family medical history. They will use this information to decide whether to accept you and what to charge.
Some insurers will deny your process outright if you have certain conditions. Others will accept you but charge a higher premium than someone the same age who applied during open enrollment. There is no federal limit on how much more they can charge based on health status outside open enrollment.
A few states have additional protections that limit medical underwriting or require insurers to offer coverage even outside open enrollment, but these vary by state. Your best protection is to explore during one of the open enrollment periods.
How to find out your exact open enrollment dates
Your initial six-month window is tied to your Part B enrollment month, not your birthday. If you are unsure when you enrolled in Part B, you can check your Medicare card — it shows your Part B effective date. Count forward six months from that date to find when your window closes.
You can also call Medicare directly at 1-800-MEDICARE (1-800-633-4227) and ask when your Medigap open enrollment period ends. They can tell you the exact dates based on your enrollment records.
For the annual October-December window, the dates are the same every year: October 15 through December 7. You do not need to do anything to "set up" this period — it is automatic for anyone on Medicare.
Switching plans during open enrollment versus outside it
| Situation | may provide Issue | Medical Underwriting |
|---|---|---|
| Initial 6-month window after Part B enrollment | Yes — no health questions, no higher premiums | Not used |
| October 15 – December 7 each year | Yes — no health questions, no higher premiums | Not used |
| Any other time of year | Not available | Yes — insurer asks health questions and can deny or charge more |
Frequently Asked Questions
Can I switch Medigap plans during my initial six-month window more than once?
Yes. You can switch between different plans and different insurers as many times as you want during your six-month window, and may provide issue applies each time. However, once the window closes, you cannot switch again without medical underwriting unless the October-December annual period arrives.
What if I enrolled in Medicare Part B late — does my open enrollment window start later too?
Yes. Your six-month Medigap open enrollment window starts the month your Part B coverage begins, not the month you turn 65. If you delayed Part B enrollment, your window starts when Part B actually starts. This is why checking your Part B effective date on your Medicare card is important.
Does the October-December open enrollment explore to everyone on Medicare?
Yes, anyone with Medicare can use the October-December period to switch Medigap plans without medical questions. You do not have to be in your initial six-month window. This period happens every year and is open to all beneficiaries.
If I explore for Medigap outside open enrollment and get denied, can I try again during the next open enrollment?
Yes. If you are denied outside open enrollment, you can explore again during the next available open enrollment period — either the October-December annual window or, if you have never used your initial six-month window, that window if it is still open. During open enrollment, insurers cannot deny you based on health history.
Can I explore for a different Medigap plan than the one I currently have during open enrollment?
Yes. Open enrollment allows you to switch to a different plan, a different insurer, or both. may provide issue applies to any plan you choose during the open enrollment window.