We've written down 20 things to know about Medigap plans.

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I stopped by a neighbor’s house to see how things were going and the conversation quickly shifted to Medicare. (This seems to happen frequently). To address his concerns, I had to find out what type of Medicare coverage he selected. He said he has a Medicare drug plan.

And my reply, “Then you probably also have a Medigap policy.”

He said, “A Medi-what?”

As I explained that, he had several more questions. And I know that, when one person has questions, there are many more who also have them. So here are 20 basic points to know about this important element of coverage.

1. A Medigap policy is officially known as Medicare Supplement Insurance. This is coverage administered by private insurance companies. Every Medigap policy will have the name of the insurance company in the title.

2. This is optional coverage that comes with an additional monthly premium.

3. A beneficiary must be enrolled in Medicare Part A and Part B in order to purchase a Medigap policy.

4. This is part of the Original Medicare package, an alternative to Medicare Advantage. After enrolling in Part A and Part B, an individual should purchase a stand-alone Part D prescription drug plan along with the Medigap plan.

5. Those who elected Medicare Advantage are not eligible to purchase a Medigap policy.

6. This policy helps pay some costs, such as deductibles, copayments, and coinsurance, for Medicare-covered services that would otherwise be the beneficiary’s responsibility. In other words, this policy helps to cover the gaps in Medicare left by Part A and Part B.

7. Any Medigap policy must cover four benefits:

• Part A hospital copayment for days 61-90 and 91-150
• Part A hospice coinsurance for inpatient respite stays and hospice-related drugs
• Part B 20% coinsurance after meeting the Part B deductible, and
• First three pints of blood.

8. Then plans can choose to cover these additional benefits:

• Part A hospital deductible for inpatient stays
• Part A skilled nursing facility copayment for days 21-100 (Medicare covers the first 20 days of a qualified stay.)
• Medicare Part B excess charges (This applies when a provider charges more than the Medicare-approved amount.)
• Foreign travel emergency, which covers up to 80% of medically necessary care outside the U.S.

(Find the 2026 Part A and Part B costs here.)

9. In 47 states, Medigap plans are standardized by 10 letters – A, B, C, D, F, G, K, L, M and N. (The missing letters represent plans that have disappeared or are no longer available to new policy holders.) Each letter represents a unique package of benefits and cost sharing. For example, Plan A is bare bones, covering only four benefits. On the other end of the spectrum is Plan F, which covers all benefits.

Find a chart of benefits by plan letter on medicare.gov.

10. Each lettered-plan, offered by any insurance company, must offer the same exact benefits, no matter the premiums. As a result, it’s possible to compare policies based solely upon the companies, agents and prices.

11. There are high-deductible versions of Plan F and Plan G available. The beneficiary pays all Medicare-covered costs, until reaching the deductible and then the policy starts paying.

12. Massachusetts, Minnesota and Wisconsin have their own models. These states standardized their plans before the federal government did so they are exempt from the current letter model.

13. A Medicare Select plan is available in some areas. The premiums may be lower but these plans generally have a network of participating providers. Those who use out-of-network providers may have to pay some or all of the costs that Part A and Part B don’t cover.

14. Since January 1, 2020, insurers cannot sell to newly eligible beneficiaries Medigap policies that cover the Part B deductible. Those who purchased a policy with this benefit (Plan C or Plan F) prior to 2020 can continue with the coverage and do not have to pay the deductible.

15. Every state has its own list of companies authorized to sell plans.

16. There is no worry over networks with a Medigap policy. Because this coverage works with Part A and Part B, beneficiaries can see any provider who accepts Medicare assignment, anywhere in the United States or its territories. (Find providers in the Physician Compare database on medicare.gov.)

17. Part A and Part B with a Medigap policy offer a “pay now” approach to Medicare coverage. Pick a package of benefits, pay the premium and out-of-pocket expenses are predictable. For example, Plan G is the most popular Medigap plan. Once the beneficiary meets the Part B deductible ($283 in 2026) and then sees providers who accept Medicare, there are no additional costs for the remainder of the calendar year. That means, no writing checks for every visit or facing an unexpected cost.

18. Depending on the state of residence, a beneficiary may not be able to change Medigap policies down the road so it’s very important to choose wisely. However, know that if premiums are paid on time, the policy is guaranteed renewable. The insurer cannot raise premiums or cancel coverage just because of a major change in health.

19. Medigap policies are very stable so there is no open enrollment period. About the only thing that changes is the monthly premium. Policy holders can apply for a new plan at anytime but they may be subject to medical underwriting, an evaluation of health status and history

20. One Medigap policy covers only one person. There are Medigap insurers that offer discounts, lower premiums when two people with the same address purchase the same policy. These discounts go by different names, such as household or multi-insurer.

This is a quick introduction to Medigap policies. Before making a choice:

• Study your options.
• Identify benefits that are important.
• Check out the Medigap policies in your area in the Medicare Plan Finder.

This probably seems like a lot of information that is just too complex to handle. However, Medigap policies are standardized so, once you understand the basics and decide what benefits you need, you can compare the available offerings. A key element, as always, is giving yourself enough time to do your research and make smart decisions.