Medigap (Medicare Supplement)

Original Medicare pays most of the bill when you are sick, but it leaves real money on your side of the ledger: a hospital deductible of $1,736 per benefit period in 2026, 20 percent of most outpatient charges, and, unlike nearly every other form of American health insurance, no annual cap on what you can owe ¹. A Medigap policy, formally Medicare Supplement insurance, is private coverage that picks up some or all of those leftover costs after Medicare pays first.

In 2023, about 12.5 million people, roughly 42 percent of everyone in original Medicare, carried a Medigap policy ². The product's appeal is predictability: with the most popular plans, a hospitalization or a course of chemotherapy generates little or no bill beyond the premium, and you can see any doctor or hospital in the country that accepts Medicare, with no networks, referrals, or prior authorization from the insurer.

Medigap works only with original Medicare. You cannot use one with a Medicare Advantage plan, and a Medigap policy covers no prescription drugs, so most policyholders pair it with a Part D plan. It also does not touch the things Medicare itself excludes, such as routine dental, vision, and hearing care or long-term care.

The standardized plans A to N#

Since 1992, federal law has standardized Medigap into lettered plans. Every Plan G is identical in benefits no matter which insurer sells it; only the price and the company's service differ. Ten plans are on the market today. Massachusetts, Minnesota, and Wisconsin run their own standardized systems with different plan designs ¹.

All ten plans cover the Part A hospital coinsurance ($434 a day for days 61-90 in 2026) and add a full year of hospital days after Medicare's run out ¹. The differences are in everything else:

Sources: Medicare Rights Center 2026 benefits chart and CMS announcements ¹³⁴.

Plans C, D, F, G, M, and N also cover 80 percent of emergency care during the first 60 days of foreign trips, after a $250 deductible and up to a $50,000 lifetime maximum, a benefit worth understanding before extended travel ¹. Most plans also pay the daily coinsurance for skilled nursing facility stays, $217 a day for days 21-100 in 2026 ¹.

Sources for this section: [1] [3] [4]

Why Plan G and Plan N dominate#

Congress barred Medigap plans from covering the Part B deductible for anyone who becomes eligible for Medicare on or after January 1, 2020. That closed Plans C and F, the old best-sellers, to new retirees; people who were eligible earlier can still buy or keep them ¹. As of 2023, Plan F still covered 36 percent of all policyholders, but its share shrinks every year as that group ages ².

For everyone newly eligible, Plan G is now the fullest coverage available: it pays everything on the standardized list except the annual Part B deductible, which is $283 in 2026 ⁵. Plan G held 39 percent of the entire Medigap market in 2023 and a much larger share of new sales ².

Plan N is the leading budget alternative, at about 10 percent of policyholders ². It trades a lower premium for three exposures: copays of up to $20 for office visits and $50 for emergency room visits that do not lead to admission, plus "excess charges," the up to 15 percent above Medicare's approved amount that a non-participating doctor may bill ¹. Excess charges are rare in practice and some states prohibit them, but they are the one open-ended cost Plan N leaves in place. High-deductible Plan G suits people who want catastrophic protection only: you cover the first $2,950 of gaps in 2026 yourself, in exchange for premiums that often run a third or less of standard Plan G ⁴.

Sources for this section: [1] [2] [4] [5]

What policies cost#

Premiums vary far more than benefits do. KFF found the average Medigap premium was about $217 a month in 2023 across all plans, with state averages running from $191 in Alaska to $267 in New York. Plan G averaged $164 a month, ranging from roughly $140 in the least expensive states to $236 in New York ². Because every Plan G is identical, getting quotes from several insurers, or asking a broker or your State Health Insurance Assistance Program to pull them, is one of the few pure price comparisons in insurance.

How a policy is priced matters as much as its first-year premium ⁶:

Attained-age pricing dominates in most states and looks attractive at 65, but the same policy can cost substantially more at 80. Nine states, including New York, Connecticut, Maine, and Massachusetts, require community rating for applicants 65 and older ².

Sources for this section: [2] [6]

Your one-time open enrollment window#

Federal law gives you exactly one Medigap open enrollment period: the six months that begin the first month you are 65 or older and enrolled in Part B ⁷. During that window, insurers must sell you any policy they offer at the standard price, regardless of your health. They may delay coverage of a pre-existing condition for up to six months if you lacked prior creditable coverage, but they cannot refuse you or surcharge you.

After the window closes, the default in most states is medical underwriting: insurers can review your health history and decline you, exclude nothing but charge more, or take you at standard rates, entirely at their discretion. People with diabetes, heart disease, cancer history, or many common conditions routinely find they cannot buy a policy at all, or only at steep rates.

Caution: The underwriting rules are the hidden stakes in the Medigap-versus-Medicare-Advantage decision at 65. Leaving Medicare Advantage for original Medicare later usually means passing underwriting to get a Medigap policy, and there is no guarantee you will. The timing rules and exceptions are laid out in Medicare enrollment periods.

Sources for this section: [7]

Guaranteed issue rights and state rules#

Outside the one-time window, federal "guaranteed issue rights" force insurers to sell you certain plans without underwriting in specific situations: your Medicare Advantage plan leaves your area or you move out of its service area, your employer coverage that paid after Medicare ends, your Medigap insurer goes bankrupt, or you exercise a "trial right" by dropping Medigap or joining Medicare Advantage at 65 and changing your mind within the first 12 months ⁷. Most of these rights come with a deadline of 63 days after the old coverage ends, and they generally cover Plans A, B, D, G, K, and L for people newly eligible after 2019, not necessarily the plan you would prefer.

States can be more generous, and several are. New York and Connecticut require insurers to accept applicants year-round with community-rated premiums; Maine and Massachusetts require at least an annual guaranteed-issue opportunity ². A number of other states have "birthday rules" or similar windows that let existing policyholders switch to equal or lesser plans annually without underwriting. Your State Health Insurance Assistance Program (877-839-2675) can tell you which rules apply where you live, which is worth checking before assuming you are locked in, or locked out.

Sources for this section: [2] [7]

RetiredWiki. (2026, July 6). Medigap (Medicare Supplement). https://retiredwiki.com/article/medigap