Medicare Supplement (Medigap) plans are private policies that help pay the out-of-pocket costs Original Medicare leaves behind — like deductibles, copays, and coinsurance. There are several standardized plans labeled by letter (A, B, D, G, K, L, M, N, and the older C and F), each covering a defined set of gaps so coverage is identical no matter which insurer sells it. For most new enrollees in 2026, Plan G offers the most complete coverage available, while Plan N is a popular lower-premium alternative. Here is how each plan works.
What Medigap Does
Original Medicare (Parts A and B) covers most hospital and medical care but leaves you responsible for deductibles, the 20% Part B coinsurance, and other costs with no annual out-of-pocket limit. A Medigap policy fills these gaps. You keep Original Medicare and add a supplement that pays its share of the bills, letting you see any provider that accepts Medicare nationwide.
How Medigap Plans Are Standardized
Because plans are standardized by the federal government, a Plan G from one company covers exactly the same benefits as a Plan G from another. That means you can shop primarily on price and company reliability, since the coverage itself does not change between insurers.
The Medigap Plans, Explained
Plan G — Most Complete Coverage for New Enrollees
Plan G covers nearly everything except the Part B deductible, which you pay once per year. After that, most Medicare-covered costs are paid in full.
- Best for: Enrollees who want maximum predictability and minimal surprise bills
Plan N — Lower Premium, Small Copays
Plan N offers similar coverage to Plan G but with lower premiums in exchange for small copays at doctor and emergency-room visits, and it does not cover Part B excess charges.
- Best for: Healthy enrollees comfortable with small copays to save on premiums
Plan F and Plan C — Closed to New Enrollees
Plan F was the most comprehensive plan, covering all gaps including the Part B deductible. Plan F and Plan C are only available to those eligible for Medicare before 2020; new enrollees cannot buy them.
- Best for: Existing policyholders who already have these plans
Plan A and Plan B — Basic Coverage
Plan A covers the core benefits, and Plan B adds the Part A deductible. These are lighter-coverage options.
- Best for: Enrollees wanting basic supplemental protection at a lower cost
Plan K and Plan L — Cost-Sharing Plans
These plans cover a percentage (50% for K, 75% for L) of certain costs and include an annual out-of-pocket maximum, after which they pay 100%.
- Best for: Enrollees who want lower premiums and an out-of-pocket cap
Plan D and Plan M — Middle-Ground Options
Plan D offers broad coverage without the Part B deductible, and Plan M splits the Part A deductible. Both are less common but available.
- Best for: Enrollees seeking a balance between premium and coverage
Medigap vs. Medicare Advantage
Medigap works alongside Original Medicare and lets you use any Medicare provider nationwide, with higher monthly premiums but lower surprise costs. Medicare Advantage (Part C) replaces Original Medicare with a private plan that often has lower premiums but network restrictions and copays. You cannot have both at the same time, so choosing between them is a key decision.
When to Enroll — The Open Enrollment Window
Your best time to buy Medigap is during your six-month Medigap Open Enrollment Period, which starts the month you are 65 and enrolled in Part B. During this window, insurers must sell you any plan at the best available price regardless of health history. Miss it, and you may face medical underwriting or higher premiums later.
How to Choose a Plan
- Decide how much certainty you want versus a lower premium
- Compare Plan G and Plan N for most new enrollees
- Shop multiple insurers for the same lettered plan and compare price
- Check the insurer's rate-increase history and reputation
- Enroll during your Open Enrollment Period to lock in guaranteed acceptance
Frequently Asked Questions
What is the best Medigap plan in 2026? Plan G offers the most complete coverage for new enrollees; Plan N is a strong lower-premium alternative.
Does Medigap cover prescription drugs? No — you need a separate Part D plan for prescription coverage.
Can I switch Medigap plans later? You can apply anytime, but outside your Open Enrollment Period you may face medical underwriting.
This guide is educational and not insurance advice. Medigap is an important, long-term decision — confirm current plan details and pricing with a licensed Medicare advisor or at Medicare.gov before enrolling.
