Medigap is extra insurance that helps pay some of your share of costs under Original Medicare, such as deductibles and coinsurance. Its full name is Medicare Supplement Insurance.

How Medigap Works

Medigap is sold by private insurance companies but works only with Original Medicare. Medicare pays its share first, and the Medigap policy pays according to its benefits.

You continue paying your Part B premium and pay a separate Medigap premium. If you want prescription coverage, you generally need a separate Part D plan because Medigap policies sold after 2005 do not include drug coverage.

What Does Medigap Cover?

Depending on the standardized plan letter, Medigap may help with:

  • Part A hospital coinsurance and certain additional hospital days
  • Part B coinsurance or copayments
  • The Part A deductible
  • Skilled nursing facility coinsurance
  • Limited foreign-travel emergency care

Medigap generally does not cover long-term care, routine dental or vision care, hearing aids, or private-duty nursing.

Plans are standardized in most states. For example, standard Plan G has the same benefits no matter which insurer sells it, although premiums and customer service can differ. High-deductible Plan G is a separate option that requires you to pay more before the policy pays. Compare the same version across insurers. Premiums can change even when benefits are the same. Massachusetts, Minnesota, and Wisconsin standardize policies differently.

Medigap Is Not Medicare Advantage

Medicare Advantage is another way to receive Medicare benefits. Medigap supplements Original Medicare. You cannot use Medigap to pay Medicare Advantage copayments, deductibles, or premiums.

When Is the Best Time to Buy Medigap?

Your one-time federal Medigap Open Enrollment Period lasts six months. It starts the first month you have Part B and are 65 or older.

During this period, insurers generally cannot deny you a policy or charge more because of health problems. After it ends, insurers may check your health history, called medical underwriting. They may deny your application or charge more unless you have a guaranteed-issue right, which requires them to offer you certain policies. Your state may provide more chances to buy coverage.

This timing is important: Medicare's annual October 15–December 7 Open Enrollment Period does not create a yearly right to buy any Medigap policy.

During Medigap Open Enrollment, an insurer may make you wait up to six months before covering health conditions you already have. Previous insurance that counts as creditable coverage can shorten or remove that wait. If you buy a policy using a guaranteed-issue right, it must cover those conditions without a waiting period. Ask the insurer to explain any waiting period before buying; see the official Medigap guide.

If you have Medicare before 65, check state-specific Medigap availability. The federal six-month window described here begins when you are both 65 or older and enrolled in Part B.

How to Compare Medigap Policies

Compare:

  • The same standardized letter across several insurers
  • Current premium and historical rate increases
  • Pricing method
  • Household discounts
  • Customer service and financial stability
  • Your state's enrollment and switching protections

Use Medicare's Medigap buying guidance and contact your State Insurance Department or your State Health Insurance Assistance Program (SHIP) for local rules.

Ask each insurer for the premium, pricing method, rate history, and any waiting-period explanation for the same plan letter and version. Keep those quotes together so you can compare the actual terms.

Medicare policy sources last checked: October 8, 2026.