Medicare Supplement Coverage Explained

Original Medicare covers roughly 80 percent of approved medical costs, but that remaining 20 percent has no annual cap, leaving beneficiaries exposed to potentially unlimited out-of-pocket expenses. Medicare Supplement coverage, also known as Medigap, is specifically designed to close these gaps. According to the National Association of Insurance Commissioners (NAIC), millions of beneficiaries carry Medigap policies because they provide financial predictability that Original Medicare alone cannot offer. This guide explains exactly what Medigap covers, what it does not, and how to match the right plan to your needs. It is general educational information, not insurance, legal, or financial advice, and the dollar amounts below are estimates that change every year.

What Medicare Supplement Coverage Includes

Medigap policies cover some or all of the cost-sharing that Original Medicare requires you to pay. The specific benefits depend on which plan letter you choose, but the most comprehensive plans cover the following in 2026: the Part A hospital deductible ($1,736 per benefit period), Part A coinsurance for hospital stays beyond 60 days ($434 per day for days 61-90, and $868 per day for the 60 lifetime reserve days), skilled nursing facility coinsurance ($217 per day for days 21-100), the Part B annual deductible ($283, covered by Plans C and F only), Part B coinsurance (the 20 percent of approved charges you would otherwise owe), Part B excess charges (up to 15 percent above the approved amount, on plans that include this benefit), the first three pints of blood, and 80 percent of foreign travel emergency care up to plan limits.

These figures are set by the Centers for Medicare & Medicaid Services (CMS) and are adjusted annually, so always confirm the current numbers at Medicare.gov before making decisions. Medicare Supplement coverage works automatically once your plan is in effect. When you receive a Medicare-covered service, Medicare pays its share first and then your Medigap insurer pays the remaining cost-sharing up to the plan’s coverage limits. There are no claims to file in most cases because the process is handled electronically between Medicare and your supplement insurer.

The Ten Standardized Plan Letters

Federal law standardizes Medigap into ten plans, identified by the letters A, B, C, D, F, G, K, L, M, and N. Standardization means a Plan G sold by one insurer must offer the same core benefits as a Plan G sold by any other insurer; only the price and service differ. (Massachusetts, Minnesota, and Wisconsin use their own standardization systems.) This is one of the most consumer-friendly features of the Medigap market, because it lets you compare policies on price and company reputation rather than deciphering different benefit designs.

Coverage by Plan Letter

The ten standardized Medigap plans offer different levels of coverage. Plan G is the most comprehensive option for new enrollees, covering everything except the Part B deductible. Plan N covers the same benefits as Plan G but excludes Part B excess charges and requires copays of up to $20 for office visits and up to $50 for ER visits not resulting in admission. Plans C and F, which also cover the Part B deductible, are only available to people who became Medicare-eligible before January 1, 2020; if you turned 65 or otherwise first qualified for Medicare on or after that date, you cannot buy them.

Plans K and L take a different approach, covering 50 percent (K) or 75 percent (L) of most benefits until you hit an annual out-of-pocket limit (roughly $7,000 for Plan K and $3,500 for Plan L in 2026 — confirm the current figure, as it is indexed each year). After reaching the limit, coverage is 100 percent for the rest of the year. Plans A and B offer basic coverage, omitting benefits such as the Part A deductible (Plan A) or foreign travel emergency care. Plans D and M fill in between. For a complete side-by-side comparison, see our Medicare Supplement plan comparison. If you are still deciding whether Medigap is right for you at all, our companion explainer on what Medicare supplemental insurance is covers the fundamentals.

What Medigap Does Not Cover

Understanding the boundaries of Medicare Supplement coverage is just as important as understanding what it includes. No Medigap plan sold today covers prescription drugs. If you want drug coverage, you need a standalone Medicare Part D plan, which you can pair with your Medigap policy. No Medigap plan covers routine dental, vision, or hearing services, or the eyeglasses and hearing aids that go with them. These are generally outside the scope of Original Medicare and therefore outside the scope of Medigap.

Medigap also does not cover long-term custodial care, cosmetic surgery, private-duty nursing, or services that Medicare itself does not cover. If Medicare denies a claim, your Medigap plan will not pay for it either. Medigap is strictly a supplement to Original Medicare, filling in the cost-sharing for covered services, not expanding the scope of what is covered. For information on specific coverage questions, such as whether Medicare covers Wegovy, we have dedicated articles that address individual services.

How Coverage Works in Practice

Consider a practical example. You visit a specialist for a knee evaluation. The doctor charges $300, and the Medicare-approved amount is $250. Medicare pays 80 percent of $250, which is $200. Without Medigap, you owe $50 (the remaining 20 percent coinsurance). With Plan G or Plan N, your supplement pays that $50 (Plan N would first apply its office-visit copay of up to $20). If the doctor does not accept assignment and charges the full $300, the $50 excess charge is covered by Plan G but not by Plan N.

For a hospital stay, the stakes are much higher. A seven-day hospitalization triggers the Part A deductible of $1,736 in 2026 plus various service charges. With Plan G, your out-of-pocket cost for that Part A deductible is $0 after your supplement pays it. Without Medigap, you owe the full $1,736 deductible, and it can be charged again if you start a new benefit period later in the year. This protection is why Medicare Supplement coverage is so valued by beneficiaries with significant healthcare needs.

Comparing Medigap Coverage to Medicare Advantage

Medicare Advantage plans provide an alternative form of coverage protection through annual out-of-pocket maximums (in recent years capped around $9,350 for in-network services, though the exact limit is set each year — verify the current amount). Unlike Medigap, Medicare Advantage often bundles prescription drugs, dental, vision, and hearing. However, these plans generally require you to use provider networks and may impose prior authorization for certain services.

The fundamental difference is this: Medigap fills the gaps in Original Medicare with minimal or zero cost-sharing at the point of service. Medicare Advantage replaces Original Medicare with a plan that caps your total annual spending but requires cost-sharing for each service until you hit the cap. For beneficiaries who use a lot of services, Medigap typically results in lower total annual costs. For healthier beneficiaries, Medicare Advantage may be more economical. Our Medigap vs Medicare Advantage guide provides a detailed analysis. Note that you cannot use both at the same time.

Choosing the Right Level of Coverage

Your choice among Medigap plan letters should reflect your healthcare utilization, financial situation, and risk tolerance. If you want maximum protection and are willing to pay a higher monthly premium, Plan G is the standard recommendation. Your annual out-of-pocket cost for Medicare-covered services is then limited to the $283 Part B deductible. See our Plan G guide for premium details.

If you prefer lower premiums and are comfortable with small copays, Plan N is an excellent alternative. You will pay the Part B deductible plus copays for office visits and certain ER visits, but your premium savings of roughly $30 to $70 per month often exceed these additional costs. For budget-conscious beneficiaries, Plans K and L offer the lowest premiums with partial coverage and an out-of-pocket cap. More on Plan N coverage is available in our Plan N guide.

Enrollment and Eligibility

Eligibility for Medicare Supplement coverage requires enrollment in both Medicare Part A and Part B. The optimal enrollment window is your Medigap Open Enrollment Period: six months starting the first day of the month you are both 65 or older and enrolled in Part B. During this period, coverage is guaranteed-issue regardless of your health status, and insurers cannot charge you more or refuse you because of pre-existing conditions. After this window closes, medical underwriting applies in most states, which can mean higher premiums or denial.

Certain life events trigger additional guaranteed-issue rights. These include losing employer coverage, having your Medicare Advantage plan leave your area, or moving out of your plan’s service area. Federal law specifies these situations, and some states (such as New York, Connecticut, Maine, and Massachusetts) add their own broader protections or annual switching windows. Your State Health Insurance Assistance Program (SHIP) can help you determine whether you qualify for guaranteed-issue rights outside the standard enrollment period, at no cost to you.

Frequently Asked Questions

Does Medicare Supplement coverage work in any state?

Yes. Medigap coverage works anywhere in the United States with any healthcare provider who accepts Medicare. There are no state-by-state network restrictions. This nationwide portability is one of Medigap’s most important advantages, particularly for people who travel or split the year between two homes.

Can I have Medicare Supplement coverage and Medicare Advantage at the same time?

No. You cannot hold both types of coverage simultaneously. If you enroll in Medicare Advantage, your Medigap insurer should stop charging you premiums. You must choose one approach or the other.

How much does Medicare Supplement coverage cost?

Monthly premiums vary by plan letter, age, location, gender, tobacco use, and carrier, and they are separate from the standard Part B premium ($202.90 in 2026). As a rough guide, Plan G premiums often range from about $120 to $300 and Plan N from about $80 to $220, but these are estimates only. Visit our cost guide for detailed pricing breakdowns, and always request current quotes.

Does Medigap cover telehealth?

Yes. If Medicare Part B covers a telehealth service, your Medigap plan pays the corresponding coinsurance just as it would for an in-person visit. The same plan-specific rules apply, including any applicable copays under Plan N.

What is the difference between Medigap and Medicare Supplemental Insurance?

They are two names for the same product: standardized private policies that fill the gaps in Original Medicare. We use both terms interchangeably. For a plain-language overview aimed at people new to the topic, see what Medicare supplemental insurance is.

Getting the Most From Your Coverage

Medicare Supplement coverage transforms the unpredictable cost-sharing of Original Medicare into a manageable, known expense. Whether you choose the comprehensive protection of Plan G, the balanced value of Plan N, or the budget-friendly partial coverage of Plans K or L, Medigap gives you financial security and the freedom to see any Medicare-participating provider nationwide. Enroll during your guaranteed-issue window, compare carriers through your state insurance department, and use our healthcare policy guide to inform your decision. The right coverage protects both your health and your retirement savings.

Sources

• Medicare.gov — Medigap (Medicare Supplement Insurance) basics, plan-comparison tool, and 2026 Medicare costs (Part A/B deductibles, coinsurance, and premiums)
• Centers for Medicare & Medicaid Services (CMS) — 2026 Medicare Parts A and B premiums and deductibles fact sheets
• National Association of Insurance Commissioners (NAIC) — Medicare Supplement (Medigap) model regulation, standardized plan framework, and enrollment data