Medigap Plan M is a Medicare Supplement Insurance plan that covers certain out-of-pocket expenses for Medicare members, including copays, coinsurance and deductibles.

Plan M is nearly identical to Medigap Plan D, which is one of the more comprehensive plans. Here’s the difference: While Plan D covers 100% of the Medicare Part A deductible, Plan M covers only 50%, but Plan M might have lower premiums as a result.

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How it works
When Medicare pays for services, you’re responsible for certain out-of-pocket costs unless you have Medicare Supplement Insurance, or Medigap, to help cover them. Medigap plans are only for Original Medicare members — Medicare Advantage members can't buy a Medigap plan.

There are 10 standardized Medigap plans available in most states (except Massachusetts, Minnesota and Wisconsin, which use different standards). The plans differ in terms of coverage for services, out-of-pocket limits and premium costs.

Medigap Plan M pays for the full cost of most of the services it covers, but it covers only half of the Medicare Part A deductible. That deductible is $1,600 in 2023, so under Plan M, you would be responsible for $800.

What Medigap Plan M covers
Here’s what Medigap Plan M covers, according to Medicare.gov:

Part A coinsurance and hospital costs up to an additional 365 days after Medicare benefits are used up.

Part A deductible (50%).

Part A hospice care coinsurance or copayment.

Part B coinsurance or copayment.

Skilled nursing facility care coinsurance.

Blood transfusion (first three pints).

Medically necessary emergency health care services for the first 60 days when traveling outside the U.S. Deductible and limitations apply.

What Medigap Plan M doesn’t cover
Medigap Plan M doesn’t cover one benefit that’s included in some other plans available to new Medicare members: Medicare Part B excess charges (if a provider is permitted to charge more than Medicare’s approved amount and does so).

Additionally, all Medigap plans, including Plan M, sold to new Medicare members don’t cover the following:

Part B deductible (since 2020, new Medicare members can’t buy any plan that covers the Part B deductible, although existing members may own older plans that do).

Prescription drugs.

Long-term care (like non-skilled care you get in a nursing home).

Dental care.

Vision care.

Private-duty nursing.

How much does Medigap Plan M cost?
Medigap plans are standardized and regulated by the government but sold by private companies. Those companies set premiums according to factors including age, location and tobacco use. In a representative North Carolina ZIP code (27406), monthly Medigap Plan M premiums for a 65-year-old nonsmoker range from $72 to $274.

To find out what a Medigap Plan M policy would cost you, visit Medicare.gov.

» MORE: How much does a Medicare Supplement Insurance plan cost?

Your Medigap open enrollment period is the easiest and least expensive time to enroll in a Medigap plan.

This period happens only once. It starts once you’re 65 and enrolled in Medicare Part B, and lasts for six months. (If you're still working after 65 and covered by a group employer plan that is deemed creditable coverage, your six-month period starts after you’ve ended active employment or no longer have that insurance.)

Medigap policies are cheapest and easiest to get during this open enrollment period because insurance companies aren’t allowed to factor your health or medical history into your price. After the period ends, the prices may go up or you may be denied coverage due to your health status or medical history.

In some states, insurance companies sell Medigap plans to those under 65 who are living with a disability and are eligible for Medicare. You can find more information through your State Health Insurance Assistance Program, or SHIP.

If you have questions about Medicare, visit Medicare.gov or call 800-633-4227 (TTY: 877-486-2048).aa