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Medigap Open Enrollment Period Explained: The Best Time to Buy a Medicare Supplement
Last Modified: 10/05/2026 | Reviewed by Keith Armbrecht (NPN 634015)
Quick Summary
Your Medigap Open Enrollment Period is a one-time 6-month period that begins the first month you’re age 65 or older and enrolled in Medicare Part B.
During this period, federal law gives you important protections when purchasing Medicare Supplement insurance. An insurance company generally can’t deny you a Medigap policy because of your health or charge you more because of past or present health problems.
Unlike Medicare’s Annual Enrollment Period, your Medigap Open Enrollment Period doesn’t happen every year. (Medicare)
Key Facts
- Medigap Open Enrollment generally lasts 6 months.
- It begins when you’re 65 or older and your Medicare Part B coverage starts.
- It is generally a one-time enrollment period.
- It doesn’t repeat every fall.
- During this period, insurers can’t use medical underwriting to deny your Medigap application.
- Your health can’t be used to increase the price during this federally protected enrollment period.
- You can generally select any Medigap policy sold to people in your situation in your state.
- After this period ends, medical underwriting may apply.
- An insurer may be allowed to deny your application after your Open Enrollment Period unless you have a guaranteed-issue right or additional state protection.
- State laws may provide rights beyond federal requirements. (Medicare)
When Does Your Medigap Open Enrollment Period Start?
Your six-month period generally begins on the first day of the month in which both of these are true:
You are age 65 or older
and
Your Medicare Part B coverage is effective
Example
You turn 65 in June and Medicare Part B begins June 1.
Your Medigap Open Enrollment Period generally runs:
June through November
What If You Delay Part B Because You’re Still Working?
This is important.
If you’re 65 or older and delay Medicare Part B because you have qualifying employer coverage, your Medigap Open Enrollment Period generally doesn’t begin until your Part B coverage starts.
That can allow someone retiring at 68, 70 or later to have their federal six-month Medigap Open Enrollment Period when they eventually enroll in Part B.
Why Is This Period So Important?
Outside your protected enrollment period, insurance companies may generally be permitted to ask medical questions and use medical underwriting.
Depending on your health, you could:
- Be denied a policy
- Have fewer available options
- Potentially pay more where permitted
That’s why your initial Medigap selection deserves careful consideration.
Is This the Same as Medicare Open Enrollment?
No.
Medicare Annual Enrollment
October 15–December 7
Primarily relates to Medicare Advantage and Medicare prescription drug plans.
Medigap Open Enrollment
Your personal six-month window associated with beginning Part B at age 65 or older.
These are entirely different enrollment periods.
Video Explanation from Keith
Don’t Miss Your Medigap Open Enrollment Period
Keith's Take
I consider your Medigap Open Enrollment Period one of the most valuable Medicare protections you’ll ever have.
During these six months, your health generally isn’t standing between you and the Medicare Supplement plan you want.
The mistake is assuming:
“I’ll just pick something now and change it whenever I want.”
Depending on your state and your health, changing later may require medical underwriting.
That’s why I want to get the initial choice right.
Compare Plan G, Plan N, premiums, companies and long-term value while you have your strongest federal enrollment protection.
Keith Armbrecht
Medicare on Video
Frequently Asked Questions About Medigap Open Enrollment
Q. How long is Medigap Open Enrollment?
A. Six months.
Q. Does it happen every year?
A. No. Federal Medigap Open Enrollment is generally a one-time period.
Q. When does it begin?
A. The first month you're at least 65 and enrolled in Medicare Part B.
Q. What if I delay Part B until age 68?
A. Your federal Medigap Open Enrollment Period generally begins when your Part B becomes effective, assuming you're 65 or older.
Q. Can an insurance company deny me during this period?
A. An insurer can't use medical underwriting to deny your application during your federally protected Medigap Open Enrollment Period.
Q. Can my health make my premium higher during this period?
A. Federal Medigap protections prevent insurers from pricing the policy based on your past or present health problems during this period.
Q. What happens when the six months end?
A. Medical underwriting may apply unless you have a guaranteed-issue right or another protection under state law.
Q. Is October 15–December 7 a Medigap open enrollment period?
A. No.
Official Government Sources
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