Medicare Supplement Insurance
Medicare Supplement Insurance, often called Medigap, is private insurance designed to help pay certain out-of-pocket costs left by Original Medicare. It works alongside Medicare Parts A and B and does not replace Original Medicare.
What Is Medicare Supplement Insurance?
Medicare Supplement (Medigap) is private insurance sold by licensed insurance carriers that is designed to help pay certain costs not covered by Original Medicare — such as deductibles, copayments, and coinsurance. It works alongside Original Medicare; the policyholder must maintain Medicare Part A and Part B enrollment.
In most states, Medigap plans are standardized by the federal government, which means the same plan letter (such as Plan G or Plan N) provides the same core benefits regardless of which insurance company sells it. Premiums and customer service, however, vary by carrier, location, age, and other factors.
Medigap works with Original Medicare — it generally cannot be used with a Medicare Advantage plan to pay Medicare Advantage cost-sharing. A person who has Medicare Advantage and a Medigap policy would generally receive no benefit from the Medigap policy for Medicare Advantage plan costs.
Key Features of Medicare Supplement
Medigap works alongside Original Medicare. The following describes how these plans generally work — specific plan terms and state rules vary.
Works With Original Medicare
Medigap supplements Original Medicare — it does not replace it. When you receive a Medicare-covered service, Original Medicare pays its share first. Your Medigap plan then pays some or all of the remaining costs, depending on the plan letter and the specific service. The policyholder must remain enrolled in Medicare Part A and Part B.
Certain Deductibles & Cost-Sharing
Depending on the plan letter, a Medigap policy may help cover the Medicare Part A deductible, Medicare Part B coinsurance, skilled nursing facility coinsurance, and other cost-sharing items defined in the policy. The specific benefits covered depend on the plan letter you choose. Benefits vary by letter — review the standardized benefit chart for the plans available in your state.
Standardized Plan Letters
In most states, Medigap plans are standardized by the federal government into plan letters (such as Plan A, Plan B, Plan G, Plan N, and others). The core benefits for each letter are the same regardless of which carrier sells it — though not all letters are offered by all carriers or in all states. Plans C and F are generally not available to people who became eligible for Medicare on or after January 1, 2020. People who were eligible for Medicare before that date may still be able to buy these plans if they otherwise qualify and the plan is offered in their area. Wisconsin, Massachusetts, and Minnesota have their own standardization rules.
Prescription Drug Coverage
Medigap policies sold after 2005 do not include outpatient prescription drug coverage. Beneficiaries who have Original Medicare and Medigap but want prescription drug coverage typically need to enroll in a standalone Medicare Part D plan separately. Enrolling in Part D at the right time helps avoid late enrollment penalties.
Cannot Be Combined With Medicare Advantage
A Medicare Supplement plan generally cannot be used to cover Medicare Advantage cost-sharing. If you are enrolled in Medicare Advantage, a Medigap policy would not pay benefits for plan costs. If you are considering switching from Medicare Advantage back to Original Medicare, discuss your Medigap options with a licensed agent before making changes.
Provider Access
With Original Medicare and a Medigap policy, you can generally see any provider in the United States who accepts Medicare — without referrals in most cases. This broad provider access is a key distinction from most Medicare Advantage plans, which typically limit you to a network. Medicare Advantage provider networks do not apply to Medigap beneficiaries.
Evaluating Medicare Supplement Plans
Because the core benefits for each plan letter are standardized, comparing Medigap plans within the same letter is largely a matter of evaluating premium, carrier, and other factors beyond the benefits themselves.
- Plan letter: The plan letter determines which benefits are covered. Understand what each letter covers before comparing premiums.
- Monthly premium: Premiums for the same plan letter vary by carrier, location, age, gender (where permitted by state law), and tobacco use status.
- Premium pricing method: Carriers use different pricing methods — community-rated, issue-age-rated, or attained-age-rated — that affect how your premium may change over time. Understand the method before enrolling.
- Household discounts: Some carriers offer premium discounts when two eligible members of a household are enrolled. Availability and amount vary by carrier and state.
- Rate history: A carrier's history of rate increases may be relevant when comparing long-term premium stability — though past increases do not guarantee future increases or stability.
- Financial strength and service: Consider carrier financial ratings and customer service reputation, since a Medigap policy is a long-term relationship.
- Foreign-travel emergency benefit: Some Medigap plan letters include a benefit for emergency care received outside the United States, subject to a lifetime limit and deductible. Review the specific plan for details.
- State-specific rules: Some states have additional Medigap protections or differ from federal standardization. Confirm applicable state rules with a licensed agent.
What to Keep in Mind
- Medigap plans do not typically cover routine dental, routine vision, hearing aids, custodial long-term care, or outpatient prescription drugs.
- Benefits and enrollment protections vary by state. Some states offer protections beyond federal minimums; others follow federal rules closely.
- Premiums can increase over time. A low initial premium is not a guarantee of long-term affordability.
- Plans with the same letter may have significantly different premiums depending on the carrier, location, and pricing method.
- Outside of protected enrollment rights, applying for Medigap may require medical underwriting in most states — meaning a carrier may be able to decline coverage or charge more based on health conditions.
When You Can Enroll in Medigap
Enrollment timing matters significantly for Medicare Supplement. Outside protected periods, medical underwriting may apply — subject to state law.
Medigap Open Enrollment Period
Federal law provides a one-time 6-month Medigap Open Enrollment Period that starts the first month you have Medicare Part B and are age 65 or older. During this period, you can buy any Medigap policy sold in your state, and an insurance company cannot use medical underwriting to deny you coverage or charge you more because of health problems. In some circumstances, however, a waiting period may apply before the policy covers a pre-existing condition. Prior qualifying health coverage may reduce or eliminate that waiting period.
Outside the Open Enrollment Period
After your Medigap Open Enrollment Period ends, insurance carriers may use medical underwriting to decide whether to sell you a policy and at what premium — depending on the state where you live. Some states provide additional enrollment protections beyond the federal minimum. Check your state's rules before applying outside a protected period.
Guaranteed-Issue Rights
In certain situations, you may have a guaranteed-issue right that requires an insurance company to sell you certain Medigap policies without medical underwriting. These protections can apply after specific events, such as certain losses of Medicare Advantage coverage, moving out of a Medicare Advantage plan's service area, or certain situations involving the loss of employer group health coverage. The policies you have a right to buy and the deadline for applying depend on the specific event. State law may provide additional protections.
Enrolling Under Age 65
If you are under 65 and have Medicare because of a disability or End-Stage Renal Disease (ESRD), federal law generally does not require insurance companies to sell you a Medigap policy. Some states provide additional rights for people under 65. Available policies, premiums, and protections vary by state, so check the rules where you live.
Medicare Supplement — Frequently Asked Questions
Is Medigap the same as Medicare Advantage?
No. They are two different approaches to Medicare coverage. Medicare Advantage (Part C) is an alternative to Original Medicare through which a private plan delivers your Part A and Part B benefits — typically with a network. Medicare Supplement (Medigap) works alongside Original Medicare — you remain in Original Medicare as your primary coverage, and the Medigap plan helps pay certain costs Original Medicare doesn't cover. You generally cannot have both Medigap and Medicare Advantage at the same time in a way that provides benefit from both.
Can I have Medigap and Medicare Advantage together?
Generally, it is not beneficial to have both simultaneously. Medigap is designed to work with Original Medicare — it cannot be used to pay Medicare Advantage cost-sharing. If you are enrolled in Medicare Advantage and hold a Medigap policy, the Medigap policy generally provides no benefit for your Medicare Advantage plan costs. If you are considering switching from Medicare Advantage back to Original Medicare, discuss Medigap options and enrollment timing with a licensed agent before making changes, as medical underwriting may apply.
Does Medigap include prescription drug coverage?
Generally, no. Medigap policies sold after 2005 do not include outpatient prescription drug coverage. If you have Original Medicare with a Medigap policy and want coverage for outpatient prescriptions, you generally need to enroll in a standalone Medicare Part D drug plan separately. Enrolling in Part D at the right time helps avoid late enrollment penalties.
When is the best time to apply for Medigap?
The best time to apply is generally during your Medigap Open Enrollment Period — the 6-month period that starts the first month you are both age 65 or older and enrolled in Medicare Part B. During this window, carriers generally cannot use your health status to deny coverage or increase premiums. Applying outside this window may subject you to medical underwriting in most states, which means carriers may be able to deny coverage or charge more based on health conditions.
Can a company ask health questions when I apply for Medigap?
It depends on when you apply and your state's rules. During your Medigap Open Enrollment Period, an insurance company cannot use medical underwriting to deny your application or charge you more because of your health. Certain guaranteed-issue situations also protect your right to buy specific Medigap policies without medical underwriting. Outside these protected situations, insurers in many states may use medical underwriting, which can include health questions and may affect whether a policy is offered and what premium applies. Some states provide additional protections.
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We are licensed insurance agents and are not connected with or endorsed by the U.S. government or the federal Medicare program. Medicare Supplement insurance is offered by private insurance companies. Policy availability, premiums, underwriting requirements, and eligibility may vary by carrier and state.