Medigap vs Medicare Open Enrollment: What's the Difference?

Medicare provides health insurance to 69 million Americans. During Medicare open enrollment, which runs from October 15 to December 7 this year, people can enroll in the program or change plans.

You can also switch from original Medicare to a Medicare Advantage plan (or vice versa), and weigh your Part D prescription drug plan coverage against other options.

If you choose original Medicare (Part A and Part B), you can also buy a Medicare Supplement Insurance (Medigap) policy from a private insurance company to cover services and out-of-pocket costs not covered by original Medicare.

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It's important to note that you can only buy Medigap if you have original Medicare. That means you must sign up for Medicare Part A and Part B before you can buy a Medigap policy.

Medigap Open Enrollment

According to Medicare, you have a six-month Medigap Open Enrollment period, which starts the first month you have Medicare Part B (medical insurance). During these six months, you can enroll in any Medigap policy, and you can’t be denied coverage for any pre-existing health problems.

After six months, you might not be able to buy a Medigap policy, and if you can, it could cost more. The Medigap Open Enrollment period only happens once and doesn’t repeat yearly such as Medicare Open Enrollment.

Stay tuned for live updates: Medicare Open Enrollment 2026 Live Updates: We'll Be Back on December 1 for the Final Week of Open Enrollment

What is Medigap?

Most states offer 10 different Medigap plans sold by private insurance companies. They're named A-D, F, G, and K-N, and the price is the only difference between the plans.

Medigap Plan G provides the most comprehensive coverage and continues to be the most popular plan in 2025, accounting for approximately 39% of all policyholders, according to KFF. Plan F came in second (36%).

You might also be able to buy another type of Medigap policy called Medicare SELECT, which is only available in some states. If you choose a SELECT policy, you have the right to change your mind and switch to a standard Medigap policy within 12 months.

If you live in Massachusetts, Minnesota and Wisconsin, Medigap policies are standardized differently. Medigap must follow federal and state laws meant to protect you, but illegal practices by insurance companies can happen, so do your research when shopping for a Medigap policy.

What does Medigap cover?

Medigap policies help cover out-of-pocket costs, such as co-insurance, copayments and deductibles associated with original Medicare — nationwide. Some Medigap policies might also cover foreign travel emergency care, which gives you an extra layer of well-being when you travel outside the U.S.

Note: Although plans E, H, I and J are no longer sold, they still cover foreign travel emergency care if you're enrolled in one of these plans. If you want prescription drug coverage, you can enroll in a separate Medicare drug plan (Part D).

What does Medigap not cover?

Although Medigap plans cover all or part of original Medicare’s additional fees, it doesn’t cover everything, such as long-term care, elective surgeries, hearing aids, eyeglasses, vision and dental care and private-duty nursing.

Not all plans cover Part B deductibles. It's also worth noting that Medigap plans sold after 2005 don’t include prescription drug coverage.

Pros and cons of Medigap insurance

Medigap covers items and services not covered by original Medicare and significantly extends hospital, skilled nursing and travel coverage. But there are a few disadvantages worth looking at before you sign up.

Medigap and Medicare have different Open Enrollment windows and policies

The initial enrollment period for Medicare is a seven-month window, which starts three months before your 65th birthday, the month you turn 65 and the three-month period after your birth month.

If you fail to enroll for Original Medicare during the initial enrollment period, you’ll get another chance during Medicare Open Enrollment, which happens from October 15 through December 7, 2025.

You have a six-month Medigap Open Enrollment period, which starts the first month you have Medicare Part B (medical insurance). During these six months, you can enroll in any Medigap policy, but after the six-month period, you might not be able to buy a Medigap policy, or it might cost more if you do.

The Medigap Open Enrollment period only happens once and doesn’t repeat every year such as Medicare Open Enrollment. Time is of the essence.

Still working? You can sign up for Medicare even if you’re still on your employer’s health plan.

Read: Seven Medicare Changes Coming in 2026.

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