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Medigap, also called Medicare Supplement insurance, fills the holes Original Medicare leaves behind: the Part A and Part B deductibles, the 20 percent coinsurance, and hospital costs after your covered days run out. The unusual part is that Medigap plans are standardized by letter. Plan G from one insurer covers the same benefits as Plan G from another. What differs is the price and the company’s service.
There are ten standardized plans, labeled A through N. Here is what each one generally covers, so you can see the pattern instead of memorizing letters.
The core plans most people buy
Plan A is the most basic. It covers Part A coinsurance and hospital costs, Part B coinsurance, blood, and hospice care coinsurance. It does not cover either deductible, skilled nursing coinsurance, or foreign travel emergencies. It is cheap and it leaves a lot on the table.
Plan B adds the Part A deductible to everything Plan A covers. Plan C adds the Part B deductible, skilled nursing coinsurance, and foreign travel emergency coverage. Plan C is no longer available to anyone who became eligible for Medicare after January 1, 2020. If you were eligible earlier, you can still buy or keep it.
Plan D is like Plan C minus the Part B deductible, which sounds minor but matters, since the Part B deductible is the one you hit every year.
Plan F is the most complete plan ever sold. It covers everything, including both deductibles and Part B excess charges. It is also closed to new Medicare beneficiaries for the same 2020 cutoff as Plan C. If you already have it, you can keep it, but new enrollees cannot buy it.
Plan G is the new Plan F in practice. It covers everything Plan F covers except the Part B deductible, which no newly sold plan is allowed to cover anymore. For most people shopping today, Plan G is the most comprehensive option available, and it is the default recommendation for anyone who wants maximum coverage and predictable costs.
Plan N trades a lower premium for small copays: up to $20 for some office visits and up to $50 for emergency room visits that do not lead to admission. It also does not cover Part B excess charges, the extra amount some doctors can bill above the Medicare-approved rate. If your doctors all accept Medicare assignment, excess charges never come up.
The budget options
Plan K and Plan L split costs with you instead of covering them fully. Plan K pays 50 percent of most cost-sharing items, and Plan L pays 75 percent. Both have annual out-of-pocket limits, which is unusual for Medigap and makes them behave a bit like Advantage plans with a cap. Premiums are lower, but so is the protection.
Plan M covers the Part A deductible at 50 percent and skips the Part B deductible. It sits between the full plans and the cost-sharing plans.
High-deductible Plan G works like regular Plan G but with a high annual deductible you pay first. The premium is much lower. It suits healthy people who want catastrophic protection and are comfortable paying the first chunk of costs themselves in a bad year.
How to actually choose
Start with your doctors. If any of them do not accept Medicare assignment, cross Plan N off your list unless you are willing to risk excess charges. Then look at how often you use care. Frequent doctor visits make Plan G’s higher premium worth it. Rare visits make Plan N or high-deductible G worth a look. Then compare premiums across insurers for the same letter, because identical coverage at different prices is the whole point of standardization.
One timing note: the best time to buy is your six-month Medigap open enrollment period, which starts when you are 65 and enrolled in Part B. During that window, insurers cannot deny you or charge more for health conditions. After it closes, most states let insurers use medical underwriting, which makes switching plans later much harder. Our comparison of Medicare Advantage vs Medigap can help if you are still deciding between the two paths, and the Medicare parts A through D guide covers what the supplement is supplementing.
