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 NAIC data, more than 14 million 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.
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: the Part A deductible ($1,676 in 2026), Part A coinsurance for hospital stays beyond 60 days ($419 per day for days 61-90, $838 per day for lifetime reserve days), skilled nursing facility coinsurance ($209.50 per day for days 21-100), the Part B annual deductible ($257 in 2026, 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 approved amounts), the first three pints of blood, and 80 percent of foreign travel emergency care.
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.
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 those who became Medicare-eligible before January 1, 2020.
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 of $7,060 (K) or $3,530 (L) in 2026. After reaching the limit, coverage is 100 percent for the rest of the year. Plans A and B offer basic coverage, omitting benefits like the Part A deductible (Plan A) or foreign travel emergency care (Plan A). Plans D and M fill in between. For a complete side-by-side comparison, see our Medicare Supplement plan comparison.
What Medigap Does Not Cover
Understanding the boundaries of Medicare Supplement coverage is just as important as understanding what it includes. No Medigap plan 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. These are outside the scope of Original Medicare and therefore outside the scope of Medigap.
Medigap also does not cover long-term care, cosmetic surgery, 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. 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 might generate a Part A deductible of $1,676 plus various service charges. With Plan G, your out-of-pocket cost for the stay is $0 after your supplement pays the deductible. Without Medigap, you owe the full $1,676 deductible and potentially more for any subsequent benefit periods within the same 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, which are capped at $9,350 for in-network services in 2026. Unlike Medigap, Medicare Advantage often includes prescription drugs, dental, vision, and hearing. However, these plans 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.
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 is limited to the $257 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 $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 turn 65 and have Part B. During this period, coverage is guaranteed regardless of health status. After this window, medical underwriting applies in most states.
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 add their own protections. Your state SHIP program can help you determine whether you qualify for guaranteed-issue rights outside the standard enrollment period.
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.
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. Plan G premiums typically range from $120 to $300. Plan N premiums range from $80 to $220. Visit our cost guide for detailed pricing breakdowns.
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.
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.