Medicare supplement insurance, also known as Medigap, is an option for people enrolled in original Medicare. Medigap plans are standardized, and the main differences among them are availability and costs.

Private health insurance companies offer Medigap plans. These plans cover some out-of-pocket costs — such as copays, coinsurances, deductibles, and other costs — that Medicare may not cover.

We may use a few terms in this piece that can be helpful to understand when selecting the best insurance plan:

  • Deductible: This is an annual amount that a person must spend out of pocket within a certain time period before an insurer starts to fund their treatments.
  • Coinsurance: This is a percentage of a treatment cost that a person will need to self-fund. For Medicare Part B, this comes to 20%.
  • Copayment: This is a fixed dollar amount that an insured person pays when receiving certain treatments. For Medicare, this usually applies to prescription drugs.

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Medigap is supplemental insurance that can help a person enrolled in original Medicare (Part A and Part B) fill gaps in their coverage.

Although Medicare covers a significant portion of insurance costs, a person is still responsible for copays and deductibles, as well as some other costs that Medicare may not cover, such as those for blood administration.

Around 25% of people enrolled in original Medicare had a Medigap plan in 2015, according to the Kaiser Family Foundation.

Some important facts about Medigap include the following:

  • A person cannot have Medigap coverage if they have a Medicare Advantage, or Medicare Part C, plan.
  • A person must be enrolled in original Medicare to qualify for Medigap.
  • Medigap plans are standardized, and not all plans are available in every state.
  • Some Medigap plans are no longer available. For example, as of January 1, 2020, private insurance companies can no longer offer plans C or F to new enrollees. However, if a person had one of these plans before January 1, 2020, they can keep them.
  • A person will pay separate monthly premiums for their Medigap plan and for original Medicare Part B.
  • A Medigap policy covers only one person, which means that spouses must get separate policies.

There are 10 Medigap plans: A, B, C, D, F, G, K, L, M, and N. In some states, plans F and G are available as high deductible plans.

Medigap plans are standardized, which means, for example, that Medigap Plan A offers the same coverage to a person in New York as it does to a person in California.

However, three states — Massachusetts, Minnesota, and Wisconsin — standardize their Medigap plans differently. If a person living in one of these three states gets a Medigap plan, they can keep the same plan if they move to another state.

Plan C and Plan F, as well as the high deductible version of Plan F, are no longer available to new enrollees in Medicare after January 1, 2020. However, if a person was eligible for original Medicare before January 1, 2020, but chose not to enroll, they may still have access to those plans.

Medicare supplement plan comparison chart

The following table compares Medigap plans:

Medigap benefitsABCDFGKLMN
Part A coinsurance and hospital costs, up to 365 days after using up Medicare benefitsYesYesYesYesYesYesYesYesYesYes
Part B coinsurance or copaysYesYesYesYesYesYes50%75%YesYes
First 3 pints of transfused bloodYesYesYesYesYesYes50%75%YesYes
Part A hospice care coinsurance or copayYesYesYesYesYesYes50%75%YesYes
Coinsurance for skilled nursing facility careNoNoYesYesYesYes50%75%YesYes
Part A deductibleNoYesYesYesYesYes50%75%50%Yes
Part B deductibleNoNoYesNoYesNoNoNoNoNo
Part B excess chargeNoNoNoNoYesYesNoNoNoNo
Foreign travel exchange (up to the plan’s spending limits)NoNo80%80%80%80%NoNo80%80%
Out-of-pocket limit for 2020N/AN/AN/AN/AN/AN/A$6,220 in 2021$3,110 in 2021N/AN/A

Plans F and G are available as high deductible plans. These plans may cost less per month, but a person must pay costs to a certain limit — which is $2,340 in 2021 — before the policy starts to pay.

Medigap plans and coverage options

For ease of plan comparison, the list below provides a brief overview of each plan’s coverage and costs.

People should note that plans in Massachusetts, Minnesota, and Wisconsin are standardized differently.

All policies may offer additional benefits, and a person can check the details with the plan provider or by using this online tool.

Plan A

A person who is hospitalized will pay the Part A deductible for days 1 to 60, then all costs are covered up to day 365.

There is 100% coverage for blood provided in a hospital inpatient setting and for hospice care. Coinsurance for skilled nursing facilities is not covered.

A person will pay the costs for the monthly premium, the hospital (Part A) deductible, and the medical (Part B) deductible. They will generally pay $0 coinsurance and copays for approved Part B services.

Plan B

Plan B provides similar coverage to Plan A but offers 100% coverage for hospital stays up to day 365.

A person will pay the costs for the monthly premium and the deductible. They will generally pay $0 coinsurance and copays for approved Part B services.

Plan C

A person with Plan C will have coverage for skilled nursing facilities, as well as foreign travel emergencies with costs of $250, then 20% to a lifetime maximum of $50,000.

In addition, they will not pay the Part A or Part B deductibles. A person will generally pay $0 coinsurance and copays for approved Part B services.

However, Plan C may not be available to people under age 65 years or those who turned 65 years old on or after January 1, 2020.

Plan D

This plan offers similar coverage to Plan C, though a person will pay the Part B deductible and Part B excess charges. They will generally pay $0 coinsurance and copays for approved Part B services.

Plan F

This plan is not available to people under age 65 years or those who turned 65 years old on or after January 1, 2020.

The plan offers comprehensive 100% coverage for hospitalization and skilled nursing care and has zero costs for the Part A deductible, the Part B deductible, and Part B excess charges.

It also provides foreign travel emergency coverage. A person will generally pay $0 coinsurance and copays for approved Part B services.

Plan F high deductible

This plan is not available to people under age 65 years or those who turned 65 years old on or after January 1, 2020.

It provides similar coverage to Plan F, and a person will generally pay $0 coinsurance and copays for approved Part B services, after the $2,340 deductible.

Plan G

Plan G also provides comprehensive 100% coverage for hospitalization, skilled nursing care, and foreign travel emergencies.

It has zero costs for Part A deductible and Part B excess charges, though a person will pay the Part B deductible. They will generally pay $0 coinsurance and copays for approved Part B services.

Plan G high deductible

This plan provides similar coverage to Plan G, and a person will generally pay $0 coinsurance and copays for approved Part B services, after the $2,340 deductible.

Plan K

A person with Plan K will have some coverage for skilled nursing facilities, as well as the Part A deductible. However, there is no coverage for the Part B deductible, Part B excess charges, or foreign travel emergencies.

A person will generally pay 10% of the coinsurance and copays for approved Part B services to a maximum of $6,220. Coverage is then 100%.

Plan L

A person with Plan L will have more coverage for skilled nursing facilities, and the Part A deductible, than Plan K. However, there is no coverage for the Part B deductible, Part B excess charges, or foreign travel emergencies.

A person will generally pay 5% of the coinsurance and copays for approved Part B services to a maximum of $3,110. Coverage is then 100%.

Plan M

A person with Plan M will have coverage for skilled nursing facilities, the Part A deductible, and foreign travel emergencies. However, there is no coverage for the Part B deductible or excess charges.

A person will generally pay $0 coinsurance and copays for approved Part B services.

Plan N

A person with Plan N will have coverage for skilled nursing facilities, the Part A deductible, and foreign travel emergencies. However, there is no coverage for the Part B deductible or excess charges.

A person will generally pay $0 coinsurance for approved Part B services, though there may be some $20 and $50 copays.

The main differences among Medigap plans are costs and coverage. When choosing a plan, a person may wish to consider the following factors:

  • For travel outside the United States, some policies offer up to 80% healthcare coverage.
  • Some Medigap plans may offer more coverage for out-of-pocket costs than for catastrophic costs.
  • People may need to balance coverage limits for out-of-pocket costs against the potential monthly premium.

A person may decide on the best Medigap plan for them by comparing the coverage and monthly premiums.

Medigap premiums can vary based on several factors. These factors include:

  • Region: Private health insurance companies may vary their costs based on what they typically pay out in a given area.
  • Guaranteed issue period: During this period, private health insurance companies cannot deny a plan to a person based on their age or preexisting health conditions. A person is in a guaranteed issue period when they first qualify for Medicare or when they move out of an area where they had a Medicare Advantage plan and return to original Medicare.
  • Preexisting health conditions: If a person is not in a guaranteed issue period, a private health insurance company can deny them coverage based on their preexisting conditions, such as if the person smokes, or they may charge a higher premium.
  • Age: As a general rule, Medigap premiums increase as a person gets older. However, some states have regulations that prohibit Medigap companies from increasing their plan premiums based on age. These states include Arkansas, Connecticut, Massachusetts, Maine, Minnesota, New York, Vermont, and Washington.
  • Plan: In general, a Medigap plan that offers comprehensive coverage may also have a high monthly premium.

Medicare’s online search tool can help a person compare Medigap plans, including costs and coverage. Using their zip code, a person can view available plans and then contact the company directly to ask about enrolling.

Most companies will allow a person to enroll in Medigap online, over the phone, or by mail.

Some companies may offer varying discounts. This may be the case when a member of the person’s household enrolls or if the person enrolls online.

While a person is in a guaranteed issue period, they may get the best monthly premiums. However, people can enroll in a Medigap plan any time an insurance company offers them a policy.

Original Medicare does not have out-of-pocket limits for spending. Medigap plans may help keep a person’s out-of-pocket costs low.

However, people should weigh the costs of their monthly premium against the costs of coverage. They can use these considerations to determine the best plan and an acceptable monthly premium for them.