Medicare Supplement (Medigap) Plans Explained: Choosing the Right One in 2026

If you are moving to Original Medicare, one question decides how predictable your medical bills will be for the rest of your life: do you add a Medicare Supplement plan, and if so, which one? These plans — almost everyone calls them Medigap — exist to fill the holes that Original Medicare leaves in your coverage. Get the choice right and a hospital stay becomes a known, budgetable cost. Get it wrong, or skip it, and a single bad health year can run into many thousands of dollars.

Here is the short answer up front. Medigap plans are standardized by the federal government into ten versions labeled A through N. Because they are standardized, the benefits of any given letter are identical from one insurer to the next — a Plan G from a national carrier covers exactly what a Plan G from a regional carrier does. That makes your real job refreshingly simple: pick the letter whose coverage fits your comfort with risk, then shop that same letter on price and service. For most people newly eligible in 2026, the decision comes down to a handful of plans — usually G, N, or a high-deductible G.

At TSM Life & Health we believe in educating first and planning second, so this guide walks through all of it in plain English: how Medigap works alongside Parts A and B, what every plan letter covers, how insurers price these policies, how Medigap compares with Medicare Advantage, and — crucially — the enrollment windows that protect you from being turned down for your health. Every figure below is sourced to Medicare.gov, CMS or KFF, and we tell you the plan year.

What Medigap is and how it works with Original Medicare

Original Medicare covers a great deal, but it was never designed to cover everything. Part A pays for inpatient hospital care after you meet a per-benefit-period deductible — $1,736 in 2026, per CMS. Part B pays for doctor visits and outpatient care, but only after a smaller annual deductible ($283 in 2026), and then it generally pays 80% of the approved amount, leaving you responsible for the other 20% — with no cap. That last phrase is the whole reason Medigap exists. Under Original Medicare alone, there is no annual ceiling on your share of the bill.

A Medigap policy slides in behind Original Medicare and pays some or all of those leftover costs — the deductibles, the daily hospital coinsurance, the 20% Part B coinsurance, and more, depending on the plan letter you choose. When you have a comprehensive Medigap plan, the arithmetic of a medical event becomes far simpler: Medicare pays its share, your Medigap plan pays most or all of what is left, and you often owe little or nothing at the point of care.

Three ground rules make Medigap easy to understand:

• It only works with Original Medicare. You must be enrolled in Parts A and B. You cannot pair a Medigap plan with a Medicare Advantage plan — in fact it is illegal for someone to sell you one while you are in Advantage, unless you are switching back to Original Medicare.
• One policy covers one person. Unlike employer coverage, a Medigap policy is individual. If you and your spouse both want a supplement, you each buy your own.
• It does not include prescription drugs. Medigap plans sold today have no drug coverage, so nearly everyone adds a stand-alone Part D plan. In 2026 all Part D plans include the new $2,000 annual cap on out-of-pocket drug costs — a change we cover in our guide to the key Medicare changes for 2026.

Put together, the "Original Medicare route" for most people is a three-part package: Original Medicare (Parts A and B) + a Medigap plan + a Part D drug plan. You pay the standard Part B premium — $202.90 a month in 2026 — plus your Medigap premium and your Part D premium. In exchange, you get the freedom to see any provider in the country that accepts Medicare and, with a comprehensive supplement, bills you can predict to the dollar.

The standardized plans A through N

In most states, Medigap plans come in ten standardized designs identified by a letter: A, B, C, D, F, G, K, L, M and N. (Massachusetts, Minnesota and Wisconsin standardize their plans a little differently.) The word "standardized" is the single most useful thing to understand about Medigap. It means the federal government defines exactly what each letter must cover, so every insurer selling, say, Plan N must provide the same core benefits. A cheaper Plan N is not a skimpier Plan N — it is the identical coverage at a lower price.

That does not mean every plan is equally popular. In practice, the market has concentrated around a few letters:

• Plan G is the comprehensive favorite. It pays essentially all of your Medicare cost-sharing except the annual Part B deductible. Roughly 39% of Medigap enrollees — about 5.3 million people in 2023 — hold a Plan G, according to KFF.
• Plan N is the value-minded choice. It covers most of the same ground as G but asks you to pay small copays (up to $20 for some office visits and up to $50 for emergency-room visits that do not lead to admission) and does not cover Part B "excess charges." In return, its premium is usually lower.
• High-deductible Plan G offers Plan G-level protection only after you first pay a high annual deductible set each year by CMS (it was $2,870 in 2025, and the figure is adjusted annually). It trades a big potential out-of-pocket exposure for a much lower monthly premium — useful for healthy budgeters.
• Plans K, L and M are cost-sharing designs: they pay a percentage of certain gaps (K pays 50%, L pays 75%, M pays 50% of the Part A deductible) in exchange for lower premiums. Plans K and L also have an annual out-of-pocket limit set each year by CMS ($7,220 for K and $3,610 for L in 2025), after which they pay 100%.
• Plans A, B and D are older, more basic designs that still exist but draw far fewer new enrollees.

About 12.5 million people carried a Medigap policy in 2023 — roughly 42% of everyone in traditional Medicare, per KFF. The clear lesson from that data is that you do not need to master all ten letters. Understand what the gaps are, decide how much of that risk you want the insurer to carry, and you will naturally land on two or three finalists.

Why Plan F (and C) are closed to newly eligible people

You will still hear people talk about Plan F as the "Cadillac" plan — it covered literally every gap, including the Part B deductible, so a Plan F holder could go through a whole year owing essentially nothing beyond premiums. So why can't most people buy it anymore?

A 2015 federal law, the Medicare Access and CHIP Reauthorization Act (MACRA), prohibited Medigap plans that pay the Part B deductible from being sold to people who become eligible for Medicare on or after January 1, 2020. Both Plan F and Plan C cover the Part B deductible, so both are closed to newly eligible beneficiaries. The reasoning was that first-dollar coverage — where the patient pays nothing at all — can encourage overuse of services, and Congress wanted beneficiaries to have at least a small amount of "skin in the game."

What each plan covers: the comparison table

Here is the heart of the decision — a benefit-by-benefit look at the eight plans most people consider today. "Yes" means the plan pays that benefit in full; a percentage means it pays that share; "No" means you are on your own for that item. This reflects the standard federal Medigap benefit chart on Medicare.gov.

*Plan N pays the Part B coinsurance in full except for copays of up to $20 for some office visits and up to $50 for emergency-room visits that do not result in an inpatient admission. Plans F and C (not shown) mirror Plan G but also pay the Part B deductible; both are closed to people newly eligible on or after January 1, 2020. Dollar figures for Part A and Part B are 2026 (CMS); the K and L out-of-pocket limits shown are 2025 and are adjusted annually by CMS. Source: Medicare.gov, How to compare Medigap policies. General education, not a recommendation for any specific plan.

A few patterns jump out of that grid. Every plan covers the big one — the Part A hospital coinsurance and an extra 365 hospital days — because that is where the largest bills live. The differences show up in the middle rows: whether the plan pays your Part A deductible, your skilled-nursing coinsurance, and small extras like Part B excess charges (only Plan G among newer plans) and foreign-travel emergencies. And notice the last row: only Plans K and L come with a true annual out-of-pocket limit, because they are the ones that leave you sharing costs along the way.

The 2026 gaps a Medigap plan absorbs

To make this concrete, it helps to see the actual dollar amounts a comprehensive Medigap plan is standing between you and your wallet in 2026. These are the published Original Medicare cost-sharing figures a plan like G is designed to pay on your behalf.

Look at that Part A hospital deductible — $1,736, and it resets with each new benefit period, not once a year. Someone hospitalized twice in a year with a gap between stays could owe it twice. Add daily coinsurance of $434 once a stay passes 60 days, plus the open-ended 20% on the Part B side, and you can see why "no annual limit" is the phrase that keeps planners up at night. A comprehensive Medigap plan absorbs almost every bar on that chart. The lone gold bar — the $283 Part B deductible — is the single gap Plan G leaves to you, and the reason Plan G premiums typically undercut the now-closed Plan F.

How Medigap pricing works: community, issue-age and attained-age

Because benefits are standardized, price is where insurers actually compete — and where two identical Plan G policies can differ by hundreds of dollars a year. Nationally, KFF reports the average Medigap premium is around $217 a month across all plans, with Plan G averaging roughly $164 a month. But averages hide a lot, because insurers use three very different rating methods to set and raise your premium over time. Knowing which one a policy uses matters as much as the starting price.

Source: Medicare.gov, Costs of Medigap policies (accessed 2026-07-31). Premium averages: KFF (2023 data).

The trap is comparing only the first-year price. An attained-age policy can look like the bargain at 65 and quietly become the most expensive option by 80, precisely when switching is hardest. A community-rated or issue-age policy may cost a little more up front but hold its value as you age. Beyond the rating method, premiums also vary by your ZIP code, tobacco use, gender in some states, and household or enrollment discounts. This is exactly why comparing the same plan letter across several carriers — and asking how each one rates — is the most valuable hour you can spend. It is also the core of what an independent agent does for you at no cost.

Medigap vs. Medicare Advantage: the real trade-off

Choosing a Medigap plan is really choosing an entire approach to Medicare — the "Original Medicare route" — over the alternative, Medicare Advantage (Part C). The two distribute cost and freedom in opposite ways, and it is worth being honest that neither wins outright. We compare them in depth in our guide to Medicare Advantage vs. Original Medicare in 2026, but here is the essence as it relates to Medigap.

With Original Medicare + Medigap, you pay a higher, predictable monthly premium and, in return, most of your cost-sharing disappears. You can see any doctor or hospital in the country that accepts Medicare — no networks, no referrals, no prior authorization for your care. That freedom is especially valuable if you travel, split the year between states, or want access to out-of-state specialists.

With Medicare Advantage, you often pay little or no plan premium and get bundled extras like dental and vision, but you accept a provider network, prior authorization, and an annual out-of-pocket maximum that you could actually reach in a bad year. To make that trade-off concrete with local numbers, we pulled the 2026 Medicare Advantage landscape for Hartford County, Connecticut from the CMS plan data:

Source: CMS CY2026 Medicare Advantage / Part D Landscape, Hartford County, CT MA-PD plans (accessed 2026-07-31). In-network out-of-pocket maximums among these plans ranged from about $4,150 to $9,250.

That last figure is the crux. A Medicare Advantage enrollee in one of these plans could face up to roughly $9,250 in a serious health year before the cap stops the bleeding — and a PPO's combined in- and out-of-network exposure can be higher still. A comprehensive Medigap plan would have absorbed almost all of that. The Medigap route costs more every month you are healthy; the Advantage route can cost far more in the one year you are not. Which risk you would rather carry is a personal decision, not a math error — and it is exactly the conversation we walk clients through.

Guaranteed-issue rights and the Medigap Open Enrollment Period

This is the most important timing lesson in the entire Medigap world, and the one people most often learn too late. Medigap is medically underwritten in most states except during protected windows. Miss the window, and your health — not just your budget — can determine whether you can buy a plan at all.

Your one-time Medigap Open Enrollment Period

Your Medigap Open Enrollment Period is a one-time, six-month window that begins the first month you are both age 65 or older and enrolled in Medicare Part B. During these six months, you have "guaranteed issue" rights: an insurer must sell you any Medigap plan it offers, at its best available rate, and cannot deny you or charge more because of pre-existing conditions. This is the golden window. For most people it is the single best time in their life to lock in a comprehensive plan.

Once that window closes, the rules change in most states. Outside a protected period, an insurer can require medical underwriting — reviewing your health history and, based on it, declining your application or charging a higher premium. This is why someone who chooses Medicare Advantage at 65, develops a serious condition a few years later, and then tries to move to Original Medicare with a Medigap plan can find a supplement expensive or simply unavailable. Getting into Advantage is always easy; getting a Medigap plan later is the part that may not be.

Other guaranteed-issue situations

Federal law also grants guaranteed-issue rights in certain specific circumstances — for example, if your Medicare Advantage plan leaves your area or stops serving Medicare, if you lose other coverage through no fault of your own, or during a "trial right" if you try Advantage when first eligible and switch back within 12 months. In those cases you again get a limited window to buy certain Medigap plans without underwriting. The rules are precise, so it is worth confirming your rights before you make a move.

How to choose the right Medigap plan in 2026

There is no single "best" Medigap plan — only the best fit for your health, budget and temperament. Here is the practical sequence we use with clients:

1. Confirm the Original Medicare route is right for you. If seeing any provider nationwide, avoiding prior authorization, and having predictable bills matters to you, Medigap is likely your path. If the lowest possible monthly cost and bundled extras matter more, weigh Medicare Advantage first.
2. Pick your comfort with risk, then your letter. Want the most complete protection with one small deductible? Look at Plan G. Willing to pay modest copays for a lower premium? Consider Plan N. Healthy, budget-focused, and comfortable with a large deductible in exchange for a low premium? Look at high-deductible Plan G.
3. Shop that letter on price and rating method. Get quotes for the same plan letter from multiple carriers, and ask whether each is community-, issue-age- or attained-age-rated, plus its recent rate-increase history.
4. Add your Part D drug plan. Match a stand-alone Part D plan to your specific medications; in 2026 every Part D plan includes the $2,000 out-of-pocket cap.
5. Mind the calendar. Whenever possible, buy during your six-month Medigap Open Enrollment Period. If that window has passed, confirm your guaranteed-issue rights — and remember Connecticut's year-round protections — before applying.

Your Medigap decision does not sit in isolation, either. It connects to when you claim Social Security, how you plan for long-term care, and the rest of your retirement income picture. If you would like a neutral second opinion, our FAQ answers more common questions, and you may also find our overview of the key Medicare changes for 2026 useful before you decide.

The best Medigap plan is not the most expensive or the one with the most benefits. It is the plan whose covered gaps match the risks that would actually keep you up at night — bought at the best price for that exact letter, in the window when your health cannot be used against you.

Frequently asked questions

Written by

Keith McLiverty

Keith is the Founder & COO of TSM Life & Health, with more than 30 years in finance, taxes, medical insurance and retirement planning. He believes in educating first and planning second, so every client understands their options before making a decision. TSM Life & Health is an independent agency serving Connecticut and is not affiliated with the federal government or Medicare. We do not offer every plan available in your area.

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