What Does a Medicare Supplement Plan Actually Cover?

A Medicare supplement plan, often called Medigap, has one job: it pays the deductibles, copayments, and coinsurance that Original Medicare leaves sitting on your kitchen table. What trips people up is the alphabet. There are ten plan letters still on the market, they all cover different combinations of gaps, and every insurance company presents its own version of the chart. The good news is that the letters are standardized by federal law, so once you understand what a letter covers, you understand it everywhere.

What gaps is a Medicare supplement plan actually filling?

Original Medicare pays most of your hospital and medical bills, but not all of them, and there is no annual cap on what you can be asked to pay. Those uncapped leftovers are the gaps a supplement plan is built to close.

Here is what Original Medicare asks you to pay in 2026 before any supplement plan steps in:

That last line is the one worth reading twice. Twenty percent of a knee replacement, a cardiac procedure, or a year of chemotherapy is twenty percent of a very large number, and Original Medicare by itself never stops the meter. A supplement plan is how you put a ceiling on it.

Which benefits does each Medicare supplement plan cover?

This is the chart every conversation eventually comes back to. If a percentage appears, the plan covers that share of the benefit and you pay the rest. If a cell is blank, the plan does not cover that benefit at all.

*Plan N pays 100 percent of the Part B coinsurance, except for a copayment of up to $20 for some office visits and up to $50 for an emergency room visit that does not result in being admitted.

A few things stand out once you sit with that chart.

Every single plan covers the Part A hospital coinsurance and an extra 365 days. That is the benefit nobody talks about and everybody should. Medicare’s own hospital coverage runs out; the supplement adds a full year on top of it.

Plans K and L work differently from the rest. Instead of covering a benefit outright, they pay half or three-quarters of it until you hit the yearly out-of-pocket limit — $8,000 for Plan K and $4,000 for Plan L in 2026. Once you meet that limit and your Part B deductible, the plan pays 100 percent of covered services for the rest of the calendar year. They are the only lettered plans with a printed out-of-pocket limit — but that is not the same as being the safest. Plan G has no printed limit because it does not need one: it covers the gaps outright, so your exposure on Medicare-approved care stops at the $283 Part B deductible, not at $8,000.

Plans F and G are the only two that cover Part B excess charges. An excess charge happens when a doctor does not accept Medicare’s approved amount as payment in full and bills you up to 15 percent more. Most physicians in Jacksonville accept assignment, so this rarely comes up — but Florida does not ban excess charges, so it can.

The foreign travel benefit works the same way in every plan that has it. Plans C, D, F, G, M, and N each pay 80 percent of billed charges for emergency care abroad, after a $250 deductible for the year, up to a $50,000 lifetime maximum. Coverage applies only to care that begins in the first 60 days of a trip.

Plans F and G also come in a high-deductible version in some states. With those, you pay Medicare-covered costs up to $2,950 in 2026 before the policy pays anything. Your Part B deductible counts toward that $2,950 rather than adding to it; the foreign travel deductible above is the one amount that sits outside it. The premium is much lower. The exposure is much higher.

Why don’t I see Plans C and F on my quotes?

Because you probably became eligible for Medicare too recently. Since January 1, 2020, Medigap policies sold to people new to Medicare are not allowed to cover the Part B deductible — and covering the Part B deductible is the whole thing that made Plans C and F distinctive. That closed both plans to new enrollees.

You may also see references to Plans E, H, I, and J. Those are no longer sold at all, though people who bought them years ago can generally keep them. For most people turning 65 in Duval County or St. Johns County today, the practical menu comes down to Plan G, Plan N, high-deductible Plan G, and occasionally Plan K or L.

What do Medicare supplement plans not cover?

Just as important as the chart is the list of things no lettered plan touches, no matter which company sells it:

Those omissions are why a supplement plan is rarely the whole picture. Because Medigap does not include drug coverage, nearly everyone who buys one also enrolls in a separate Part D plan. For dental, vision, and hearing, a standalone dental, vision, and hearing plan fills the gap, and supplemental policies like hospital indemnity or critical illness coverage handle a different kind of risk entirely.

Long-term care is the biggest one. If you or a parent needs the level of care a nursing home provides, no Medigap letter helps, which is one reason we have written about the PACE program coming to Northeast Florida as an option worth understanding early.

It is also worth naming what a Medigap plan is not. It is not a Medicare Advantage plan, not a Part D drug plan, not Medicaid, not TRICARE or veterans’ benefits, and not an employer or union retiree plan. Those are all separate types of coverage with their own rules, and a few of them cannot be combined with Medigap at all.

Which plans can Florida insurance companies actually sell you?

Every company that sells Medigap in Florida has to offer Plan A. If it wants to sell anything beyond that, it must also offer either Plan C or Plan F to people who are not new to Medicare, and either Plan D or Plan G to people who are. Beyond that minimum, each carrier decides which letters it wants to sell, which is why one company’s brochure lists four plans and another lists eight.

You may also come across Medicare SELECT. Those are standardized Medigap plans that ask you to use certain hospitals and, in some cases, certain doctors in exchange for a lower premium. They are the one flavor of Medigap that comes with a network attached, and whether the network includes the systems you already use is the only question that matters. For families in Jacksonville, that usually means checking whether Baptist Health, UF Health Jacksonville, or Mayo Clinic is in it.

Standard Medigap plans have no network at all. Any provider anywhere in the country who accepts Medicare accepts your supplement, which is what makes this coverage appealing to snowbirds and to anyone who splits the year between Northeast Florida and somewhere north. If that portability is what draws you, our comparison of Medicare Advantage and Medigap in Florida walks through the trade-off in detail.

One footnote for anyone moving here from up north: Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans differently. If you carried a policy in one of those states, the letter on your old card does not map cleanly onto the Florida chart.

When are you guaranteed the right to buy one?

Sometimes a company must sell you a Medigap policy even if you have health problems. Those protected moments are worth knowing by heart, because outside of them the rules change completely.

Outside of those windows, a Florida insurance company can look at your health history, charge you more, or decline you altogether. Some states have an annual birthday rule that lets you change supplement plans without underwriting. Florida does not. Florida does extend guaranteed issue rights in a handful of specific situations, including a six-month window for people who qualify for Medicare before 65 because of a disability or end-stage renal disease, but there is no yearly do-over.

That is the single most consequential fact in this entire article. The chart above tells you what each plan covers; your open enrollment period determines whether you get to choose freely among them. Miss it, stay healthy, and you will probably still be fine. Miss it, then get a diagnosis, and the door may already have closed.

How should Northeast Florida families read this chart?

Start from the bottom of the chart, not the top. Almost everyone’s real decision in 2026 comes down to a small number of letters, and the differences between them are narrow and specific.

Plan G covers every gap on the chart above except the $283 Part B deductible. Plan N covers the same ground as Plan G except excess charges, and asks for small copays at the point of care in exchange for a lower premium. High-deductible Plan G trades a much lower premium for $2,950 of exposure before it pays. Plan K and Plan L cost less monthly and cap your year at $8,000 or $4,000 — a higher ceiling than Plan G’s effective $283, in exchange for a lower premium. That is genuinely the whole decision for most people.

Then remember the part the chart cannot show you. Because the benefits are fixed by law, two carriers selling the identical Plan G are selling the identical coverage — but not the identical price, and not the identical history of raising that price. A carrier with an attractive rate today and a pattern of steep annual increases is a more expensive plan than its quote suggests. Comparing rate stability across companies is unglamorous work, and it is where most of the money is.

At Duncan Market Insurance, Carolyn Duncan has spent more than 20 years in the insurance industry and works today as an independent broker licensed in Florida, helping people in Jacksonville, St. Augustine, and the surrounding counties read exactly these charts. We are not captive to one carrier, so we have no reason to steer you toward a particular letter or a particular company. If you would rather have someone walk the Medicare options with you than decode a benefits grid alone, that is what we are here for. Florida’s SHINE program also offers no-cost counseling through the state if you want a second perspective.

Ready to compare Medicare supplement plans for your situation?

The letters are standardized, but you are not. The right plan depends on how often you see doctors, whether you travel, how much monthly premium you are comfortable with, and how much risk you want to carry yourself. A consultation with Duncan Market Insurance is a no-cost, no-obligation conversation where we look at all of that together and give you a straight answer.

Book a consultation → · Call 904-217-8368

Sources

• Compare Medigap plan benefits, Medicare.gov
• Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare (CMS Product No. 02110)
• 2026 Medicare Parts A & B Premiums and Deductibles, CMS
• CY2026 Medigap High Deductible Options F, J, and G, CMS
• SHINE — Serving Health Insurance Needs of Elders, Florida Department of Elder Affairs

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Not connected with or endorsed by the U.S. Government or the Federal Medicare Program.