Original Medicare pays roughly 80 percent of covered medical costs, with no cap on the rest. A Medicare Supplement, also called Medigap, picks up some or all of that remaining share: deductibles, the 20 percent coinsurance, and hospital costs beyond Medicare’s limits. You keep the freedom to see any doctor who accepts Medicare, anywhere in the country.
The good news: plans are standardized
Supplement plans are named by letters, and every plan with the same letter has identical benefits by law. A Plan G from one insurer covers exactly what a Plan G from another does. What differs is the price, which is why comparing insurers matters more than comparing brochures.
The plans, letter by letter
Plan A
The basic benefits: Part A coinsurance and hospital costs, Part B coinsurance or copays, the first three pints of blood, and hospice coinsurance.
Plan B
Everything in Plan A, plus the Part A deductible.
Plan C
Adds skilled nursing coinsurance, the Part B deductible and foreign travel emergency care. Only available if you were eligible for Medicare before January 1, 2020.
Plan D
Like Plan C, but without the Part B deductible.
Plan F
The most complete coverage, including the Part B deductible and Part B excess charges. Only available if you were eligible before January 1, 2020. A high-deductible version also exists.
Plan G
Everything in Plan F except the Part B deductible. A high-deductible version is also available.
Plan K
Pays 50 percent of many costs, with a yearly out-of-pocket limit, for a lower premium.
Plan L
Pays 75 percent of many costs, with a yearly out-of-pocket limit.
Plan M
Like Plan D, but pays only half of the Part A deductible.
Plan N
Similar to Plan G, but with copays of up to $20 for some office visits and up to $50 for emergency room visits that do not lead to an admission, and no coverage for Part B excess charges.
Live in Massachusetts? Massachusetts does not use these lettered plans. It has its own standardized Supplements: the Core Plan and Supplement 1A, plus Supplement 1 for people eligible for Medicare before 2020. Rules in other states can differ too, so ask us what applies where you live.
Timing matters here more than anywhere: in the six months after you enroll in Part B, insurers must accept you regardless of your health. After that window, they can ask health questions and may charge more or decline.
What Supplements do not cover
Prescription drugs (that is what Part D is for), and generally not dental, vision or hearing. Most Supplement holders pair their plan with a Part D drug plan.
Same coverage, different prices.
Let us compare Supplement prices across insurers for your age and zip code.