Medicare Supplement Plans: what to ask, what it costs, and one number to call

Medicare supplement insurance (Medigap) exists because Original Medicare leaves real gaps, most notably the 20% coinsurance on outpatient care with no annual cap. A Medigap policy fills those gaps in exchange for a monthly premium, letting you see any provider in the country that accepts Medicare, with little paperwork and highly predictable costs. The plans themselves are standardized by letter (Plan G, Plan N, and so on), so a Plan G from one insurer pays identical benefits to a Plan G from another. Only the price and the company differ, which makes this one of the few insurance markets where shopping is genuinely simple.

The catch is timing. During your six-month Medigap open enrollment window, starting when you're 65 and enrolled in Part B, insurers must sell to you at standard rates regardless of health. Miss that window, and in most states they can decline you or charge more based on your health. That single fact should shape how carefully you make your first choice, and how skeptical you are of anyone urging a quick switch later.

What should you have ready before you call?

What should you ask before you sign? The 9-question script

This is your script. Nobody expects you to be an expert. Sound like someone who asks the right questions, and anyone good will answer all of these without flinching.

How much do medicare supplement plans cost in 2026?

Medigap benefits are standardized by plan letter, so price differences between carriers are pure price. These 2026 figures for a new 65-year-old enrollee vary by ZIP, sex, and tobacco status.

When you don't need to call anyone

We get paid when you call, so take this section as seriously as we do. Sometimes the honest answer is that you can handle it yourself or fix it cheaper first:

How Medigap works, and how it differs from Medicare Advantage

Start with the fork in the road, stated neutrally because both paths are legitimate. Medigap rides alongside Original Medicare: Medicare pays first, your supplement pays most or all of the rest, and you can see any Medicare-accepting doctor or hospital nationwide without referrals or prior authorization from the supplement. You pay a real monthly premium for that freedom, plus a separate Part D plan for drugs. Medicare Advantage replaces how your Medicare benefits are delivered: a private plan, often with a $0 premium and extras like dental or vision, but with provider networks, prior authorization requirements, and copays that accumulate toward an annual out-of-pocket maximum. Broadly, Medigap front-loads cost for predictability and access; Advantage minimizes premium and accepts managed-care trade-offs. Neither is universally right. Your health, finances, travel habits, and tolerance for networks decide it.

Within Medigap, the letters do the work. Plan G is the standard-bearer for new enrollees: it covers essentially everything Original Medicare doesn't except the annual Part B deductible (a few hundred dollars a year). Plan F, which also covered that deductible, closed to people newly eligible after January 1, 2020. Plan N runs cheaper than G in exchange for small copays on office and ER visits and exposure to 'excess charges' (the up-to-15% surcharge a minority of providers add over Medicare's rate, which some states ban outright). High-deductible Plan G offers the same backstop after a deductible of around $2,800, at a much lower premium, and suits people who can absorb routine costs but want catastrophic protection.

Identical benefits don't mean identical prices, and pricing structure matters as much as today's number. Attained-age policies start cheapest and raise rates as you age; issue-age policies price on your age at purchase; community-rated policies charge everyone the same regardless of age. All three also take general rate increases over time. A quote $15 a month cheaper today on attained-age pricing can cost more by your late 70s, so ask how the carrier prices and what its rate-increase history looks like in your state.

Finally, the switching trap. Leaving Medigap for a $0-premium Advantage plan is easy; coming back may not be. Outside your original window and a few guaranteed-issue situations (like a 'trial right' in your first year on Advantage), returning to Medigap means medical underwriting in most states, and a health condition picked up in the meantime can mean denial or high rates. A handful of states (including New York, Connecticut, Massachusetts, and others with 'birthday rules') guarantee easier switching. Anyone pitching you a switch in either direction should be able to explain exactly what rights you'd be giving up. If they can't, that's your answer about the pitch.

Red flags & good signs

Frequently asked questions

Related services