U.S. · Medigap
Your Medigap open enrollment, dated.
Enter your birth date and Part B start date to see when the six-month window opens and closes.
The Medigap open enrollment period lasts 6 months and starts on the first day of the month you are 65 or older and enrolled in Medicare Part B. During it you can buy any Medigap policy sold in your state. After it, options may be limited and costs higher.
Try it
Result
How the window is counted
Medicare.gov says the period starts the first day of the month you are 65 or older and signed up for Part B, and lasts 6 months, even if you sign up for Part B while you still have employer coverage. This calculator takes the later of your 65th birthday and your Part B date, starts the window on the first of that month, and ends it on the last day of the sixth month. A start of March 1, 2026 runs through August 31, 2026.
Worked example
Born March 15, 1961, Part B effective March 1, 2026. The 65th birthday (March 15, 2026) is later than the Part B date, so the window opens March 1, 2026 and closes August 31, 2026.
Other times you can buy
Medicare.gov lists separate rights for people who lose other coverage: generally you must apply no more than 63 days after that coverage ends, and for some Advantage plan situations you can also apply 60 days before it ends. Rights can last an extra 12 months in some cases.
Under 65
Federal law does not require companies to sell Medigap to people under 65. Some states do, and some require it only for people eligible through a disability or ESRD. Check with your State Insurance Department.
If you are still working
If you or your spouse keep employer coverage and delay Part B, the clock does not start until Part B does. Employer coverage often gives coverage similar to Medigap, so you may not need a policy yet.
Sources
Primary sources opened and checked on November 2, 2026. This page has no affiliation with any agency; confirm with the agency before you rely on an amount or date.
- Medicare.gov, When can I buy Medigap?. Read November 2, 2026.
Frequently asked questions
How long is the Medigap open enrollment period?
Six months.
When does Medigap open enrollment start?
On the first day of the month you are 65 or older and enrolled in Medicare Part B.
What protection does it give me?
Per Medicare.gov, you can buy any Medigap policy sold in your state. After the window, your options may be limited and the policy may cost more.
Does it start if I keep working and delay Part B?
The period starts once you sign up for Part B, even if you still have employer coverage.
Can I get Medigap if I am under 65?
It depends on your state. Federal law does not require companies to sell Medigap to people under 65.
Not legal, financial or benefits advice
This page summarizes Medicare.gov guidance and is not insurance advice. Everything runs in your browser; nothing you enter is sent anywhere.