Original Medicare (Parts A and B) only pays about 80% of your covered costs — the other 20% has no cap, which can get expensive fast. Medicare Supplement insurance, also called Medigap, is a private policy that pays those leftover gaps so you’re not exposed to unlimited out-of-pocket bills. Here’s how the top plans compare and how to choose.
How Medigap Works
Medigap fills gaps Original Medicare leaves by pairing a private plan with your Part A and Part B coverage. You can see any Medicare-accepting doctor nationwide, with no networks or referrals required.
Medigap plans are sold by private insurers but standardized by the federal government and labeled with letters (Plan A through Plan N). That standardization is the key consumer-protection feature: a Plan G is the same coverage no matter which company sells it — only the price and customer service differ. So once you pick a plan letter, you simply shop for the lowest premium from a financially strong carrier.
Medigap works alongside Original Medicare (not Medicare Advantage — you can’t have both). You keep the freedom to see any doctor in the country who accepts Medicare, with no networks and no referrals.
The Top Medicare Supplement Plans
Plan G — Best Overall
Plan G is the most popular choice for people newly eligible for Medicare. It covers nearly everything Original Medicare leaves behind — Part A deductible, coinsurance, copays, skilled nursing coinsurance, and foreign travel emergencies — leaving you to pay only the small annual Part B deductible. Predictable, comprehensive, and widely available.
Plan N — Best Value
Plan N has a lower premium than Plan G in exchange for small copays (up to $20 for office visits, $50 for ER visits that don’t lead to admission) and not covering Part B “excess charges.” If your doctors accept Medicare assignment (most do), Plan N can save you meaningful money each month while still capping your big risks.
Plan F — Best for Those Already Enrolled
Plan F is the most complete plan — it even covers the Part B deductible — but it’s only available if you were eligible for Medicare before January 1, 2020. If you already have Plan F you can keep it; if you’re newly eligible, Plan G is the modern equivalent.
High-Deductible Plan G — Best Low-Premium Option
A high-deductible version of Plan G offers the same comprehensive coverage but with a much lower monthly premium and a yearly deductible you pay before it kicks in. It’s ideal for healthy enrollees who want catastrophic protection at the lowest possible premium.
Plan G vs. Plan N vs. Plan F (At a Glance)
| Feature | Plan G | Plan N | Plan F* |
|---|---|---|---|
| Part A deductible | Covered | Covered | Covered |
| Part B deductible | You pay | You pay | Covered |
| Office/ER copays | None | Small copays | None |
| Part B excess charges | Covered | Not covered | Covered |
| Monthly premium | Higher | Lower | Highest |
*Plan F is available only if you were Medicare-eligible before 2020.
How to Pick the Best Medigap Plan
Start with Plan G for the most coverage, or Plan N if you want lower premiums with small copays. Always buy during your 6-month Open Enrollment window so insurers can’t deny you or charge more.
- Start with Plan G unless you want a lower premium and don’t mind small copays — then look at Plan N.
- Buy during your Medigap Open Enrollment — the 6-month window starting when you’re 65 and enrolled in Part B. During it, no insurer can deny you or charge more for health conditions. Miss it and you may face medical underwriting.
- Shop on price, not brand. Because the coverage is standardized, two Plan G policies are identical — pick a financially strong carrier with the lowest rate and a history of small annual increases.
Frequently Asked Questions
What are the top Medicare Supplement plans?
Plan G (best overall), Plan N (best value with small copays), Plan F (most complete, but only for those eligible before 2020), and High-Deductible Plan G (lowest premium). Plan G is the most popular for people new to Medicare.
What is a Medicare Supplement plan?
A Medigap policy is private insurance that pays the out-of-pocket costs Original Medicare leaves — deductibles, coinsurance, and copays — so you’re protected from the uncapped 20% you’d otherwise owe. Plans are standardized by letter and work alongside Parts A and B.
Is Medigap better than Medicare Advantage?
Neither is universally better. Medigap gives you nationwide provider freedom and predictable costs for a monthly premium; Medicare Advantage offers lower premiums and bundled extras but uses networks. Choose based on whether provider freedom or low premium matters more to you.
When should I buy a Medicare Supplement plan?
During your 6-month Medigap Open Enrollment Period, which begins when you’re 65 and enrolled in Part B. Buying then guarantees you can’t be denied or surcharged for pre-existing conditions.