Medigap plans explained: what each letter covers and when to buy

Original Medicare pays a large share of your hospital and medical bills, but not all of it. After Part B's yearly deductible you generally owe 20% of the Medicare-approved amount for doctor visits and outpatient care, and Part A has its own deductible for each hospital benefit period and daily coinsurance for long hospital and skilled nursing stays. Medicare Supplement Insurance, better known as Medigap, is private insurance built to fill those gaps.

Medigap is also one of the few Medicare decisions where timing matters more than price. Buy at the right moment and no insurer can turn you down or charge you more because of your health. Wait, and in most states an insurer can do both. This guide explains how Medigap works, what each lettered plan covers, how premiums are priced, and the enrollment windows and protections that decide whether you can buy the plan you want. It is based on two official publications from the Centers for Medicare & Medicaid Services (CMS): Choosing a Medigap Policy, the booklet CMS wrote with the National Association of Insurance Commissioners, and the Medicare & You 2027 handbook. Dollar amounts are for 2026, the latest year both publications print.

What Medigap is, and what it is not

CMS describes Medigap as extra insurance you buy from a private health insurance company to help pay your share of out-of-pocket costs in Original Medicare, like copayments, coinsurance and deductibles. When you get care, Medicare pays its share of the Medicare-approved amount first, and then your Medigap policy pays its share. Medicare does not pay any of the cost of buying a Medigap policy; you pay the insurance company a monthly premium on top of the Part B premium you pay to Medicare, which is $202.90 a month in 2026 for most people (see Part B premium).

A few basic rules shape everything else:

• You generally need both Part A and Part B to buy a Medigap policy.
• Medigap works only with Original Medicare. It is not the same thing as a Medicare Advantage Plan, which is a different way to get your Medicare coverage. A Medigap policy cannot pay Medicare Advantage deductibles, copayments, coinsurance or premiums.
• A policy covers one person. If you and your spouse both want Medigap, you each buy your own policy.
• Medigap plans sold after 2005 do not include prescription drug coverage. For drugs, you join a separate Medicare drug plan (Part D); see Part D costs.
• Insurance companies generally cannot sell you a Medigap policy if you have coverage through a Medicare Advantage Plan or Medicaid.

CMS also lists coverage that is not Medigap, even though it may help with some of the same costs: Medicare Advantage Plans, Medicare drug plans, Medicaid, employer group health plans (including the Federal Employees Health Benefits program, retiree and COBRA coverage), union plans, TRICARE, veterans' benefits, long-term care insurance, and Indian Health Service, Tribal and Urban Indian Health plans. Military retirees who have TRICARE For Life can read how that coverage works with Medicare in our TRICARE For Life guide.

Plans are standardized by letter

In most states, insurance companies can sell only standardized Medigap plans, named by letters A through D, F, G, and K through N. Every plan with the same letter offers the same basic benefits, no matter where you live or which company sells it. In CMS's words, price is the only difference between policies with the same letter sold by different companies. That makes shopping simpler than it looks: you choose the letter for the coverage, then compare companies on price.

A few details about the lineup:

• Every insurance company that sells Medigap must offer at least Plan A. Beyond that, each company decides which plans it sells.
• Plans E, H, I and J are no longer sold. If you already have one, you can generally keep it.
• Plans D and G with coverage starting on or after June 1, 2010 have different benefits than Plans D or G bought before that date.
• Massachusetts, Minnesota and Wisconsin standardize Medigap in their own way, covered in a section below.

Plans C and F and the January 1, 2020 rule

Medigap plans sold to people new to Medicare on or after January 1, 2020 are not allowed to cover the Part B deductible, which is $283 in 2026. Because covering that deductible is what sets Plans C and F apart, those two plans are no longer available to people new to Medicare. For this rule, CMS says you are new to Medicare if you turned 65 on or after January 1, 2020 and get Part A on or after January 1, 2020.

Two groups are not shut out. If you were eligible for Medicare before January 1, 2020 but have not enrolled yet, you may still be able to buy Plan C or Plan F. And people new to Medicare have the right to buy Plans D and G instead, which the handbook says give the same benefits as Plans C and F except for covering the Part B deductible.

What each plan covers

The table below summarizes the CMS benefit chart for 2026. "Basic benefits" here means the four things every plan covers at least in part: Part A coinsurance and hospital costs (up to an additional 365 days after Medicare benefits are used up), Part B coinsurance or copayments, the first 3 pints of blood, and Part A hospice care coinsurance or copayments. Plans A through D, F, G, M and N pay all of those basic benefits; Plans K and L pay the hospital costs in full but only part of the rest.

A few of the terms in that chart deserve a closer look, because they are where the plans really differ.

The Part A deductible

Part A has a deductible for each inpatient hospital benefit period: $1,736 in 2026 (see Part A costs). Plan A does not cover it. Plans B, C, D, F, G and N cover it in full, Plan M covers half, and Plans K and L cover 50% and 75%.

Skilled nursing facility coinsurance

In 2026, Original Medicare charges $217 a day for days 21 through 100 in a skilled nursing facility, and you pay all costs after day 100. The Medigap benefit covers that daily coinsurance. Plans A and B do not cover it; Plans C, D, F, G, M and N do, and Plans K and L pay part. This is skilled care, not non-skilled long-term care in a nursing home, which Medigap generally does not cover.

Part B excess charges

CMS defines an excess charge as the difference between the Medicare-approved amount and the higher amount a doctor or other provider is legally permitted to charge you. A doctor who accepts assignment agrees to take the Medicare-approved amount as payment in full and not to bill you more than the Medicare deductible and coinsurance. Only Plans F and G cover them.

Foreign travel emergency care

CMS lists medical care when you travel outside the U.S. as an example of something Original Medicare does not cover but some Medigap policies do. Plans C, D, F, G, M and N pay 80% of foreign travel emergency care, up to plan limits. Plans A, B, K and L do not cover it.

Plan N's copayments

Plan N pays 100% of the Part B coinsurance, but you pay a copayment 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 K and L: cost sharing with a ceiling

Plans K and L pay a share of most costs (50% for K, 75% for L) rather than the full amount, and they include a yearly out-of-pocket limit: $8,000 for Plan K and $4,000 for Plan L in 2026. After you meet that limit and your yearly Part B deductible, the plan pays 100% of covered services for the rest of the calendar year.

High-deductible Plans F and G

In some states, Plans F and G are also sold with a high-deductible option. With it, you pay the first $2,950 (in 2026) of deductibles, copayments and coinsurance for covered services not paid by Medicare before the Medigap policy pays anything. You also pay a separate $250 yearly deductible for foreign travel emergency care. CMS lists whether a company offers this option among the things that affect what a Medigap policy costs. As with regular Plan F, the high-deductible Plan F is not available to people new to Medicare on or after January 1, 2020.

What Medigap does not cover

Medigap fills gaps in services Medicare covers; it generally does not add services Medicare leaves out. Both CMS publications say Medigap policies generally do not cover:

• Long-term care, like non-skilled care in a nursing home.
• Vision or dental care.
• Hearing aids.
• Eyeglasses.
• Private-duty nursing.

If those are the costs you worry about, our guide to what Medicare doesn't cover goes through each gap and its narrow exceptions.

The best time to buy: your Medigap Open Enrollment Period

CMS is clear that the best time to buy a Medigap policy is during your Medigap Open Enrollment Period. It lasts 6 months and starts the first month you have Part B and are 65 or older. It is a one-time window; it does not repeat every year. Some states have additional open enrollment periods.

During those 6 months, according to the booklet, you can:

• Buy any Medigap policy sold in your state. A company cannot refuse to sell you any policy it offers, and it cannot use medical underwriting to accept or deny you because of pre-existing health problems.
• Generally get better prices and more choices. A company cannot charge you more because of your health.
• Have coverage start right away, except that a policy may make you wait for coverage of a pre-existing condition.

Medical underwriting is the process an insurer uses to decide, based on your medical history, whether to accept your application, whether to add a waiting period for pre-existing conditions (if your state allows it), and how much to charge. Outside your open enrollment period and without a guaranteed issue right, CMS warns that you may pay more, have fewer choices, and have no guarantee a company will sell you a policy if you do not meet its underwriting requirements.

Pre-existing condition waiting periods

Even in open enrollment, a Medigap company can in some cases refuse to cover your out-of-pocket costs for a pre-existing condition for up to 6 months. That exclusion can apply only to a condition treated or diagnosed within the 6 months before the policy starts, which CMS calls the look-back period. Original Medicare still covers the condition during that time; you just pay the Medicare coinsurance or copayment yourself.

Prior health coverage can shorten or eliminate the wait. If you had at least 6 months of continuous creditable coverage before applying, the company cannot make you wait. Many types of coverage count, but only if your break in coverage was no more than 63 days. When you buy with a guaranteed issue right, the company must cover all your pre-existing conditions with no waiting period.

If you are still working

Because the window starts when you sign up for Part B at 65 or older, your choice about Part B also sets your Medigap clock. If you have group health coverage through your own or your spouse's current job, CMS notes you may want to wait to sign up for Part B. Your Medigap Open Enrollment Period then will not start until you get Part B, so it is still there when the job coverage ends. Retiree coverage is different: after you retire, Medicare pays first, and CMS says retiree coverage is probably similar to a Medigap policy. Our guides to Medicare enrollment periods and the late enrollment penalties explain the Part B side of that decision.

If you are under 65

Federal law generally does not require insurance companies to sell Medigap to people under 65, so people with Medicare because of a disability or End-Stage Renal Disease may not be able to buy the policy they want, or any policy, until they turn 65. At the time CMS printed the booklet, these states required insurers to offer at least one kind of Medigap policy to people with Medicare under 65: Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, New Hampshire, New Jersey, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, South Dakota, Tennessee, Texas, Vermont and Wisconsin. Some of those states extend the right to everyone under 65 with Medicare and others only to people with a disability or ESRD. Either way, you still get your own Medigap Open Enrollment Period when you turn 65, and if you had Medicare for more than 6 months before then, you may not face a pre-existing condition waiting period.

Guaranteed issue rights: buying later with protection

Guaranteed issue rights, also called Medigap protections, let you buy certain policies outside your open enrollment period in limited situations. In those situations, the company must sell you a policy, must cover all your pre-existing conditions, and cannot charge more because of past or present health problems. These are the most common situations under federal law, from the CMS booklet:

• Your Medicare Advantage Plan leaves Medicare, stops giving care in your area, or you move out of its service area, or its network has a significant change, and you switch to Original Medicare. You can buy Plan A, B, C, D, F or G. Apply as early as 60 days before the plan coverage ends, and no later than 63 days after it ends.
• You have Original Medicare and an employer group health plan, including retiree, COBRA or union coverage, that pays after Medicare, and it is ending. You can buy Plan A, B, C, D, F or G no later than 63 days after the latest of three dates: when the coverage ends, the date on the notice saying it is ending, or the date on a claim denial if that is the only way you learn it ended.
• You move out of your Medicare SELECT policy's service area. You can buy Plan A, B, C, D, F or G in your state or the state you are moving to, from 60 days before until 63 days after the SELECT policy ends.
• Trial right for new Medicare Advantage members. If you joined a Medicare Advantage Plan or a Program of All-inclusive Care for the Elderly (PACE) when you were first eligible for Part A at 65, and within the first year you want to switch to Original Medicare, you can buy any Medigap policy sold in your state.
• Trial right after dropping Medigap. If you dropped a Medigap policy to join a Medicare Advantage Plan (or switch to Medicare SELECT) for the first time, have been in the plan less than a year, and want to come back, you can get your old policy back if the same company still sells it, or otherwise buy Plan A, B, C, D, F or G.
• Your Medigap company goes bankrupt or your policy ends through no fault of your own: Plan A, B, C, D, F or G, within 63 days.
• You leave a Medicare Advantage Plan or drop a Medigap policy because the company did not follow the rules or misled you: Plan A, B, C, D, F or G, within 63 days.

For the two trial rights, CMS notes that your rights may last an extra 12 months in certain circumstances; your State Insurance Department can tell you. The same note on Plans C and F applies throughout: people new to Medicare on or after January 1, 2020 can buy Plan D or G instead.

Proof matters. CMS advises keeping copies of letters, notices, emails or claim denials with your name on them that show your coverage ended, along with the postmarked envelope they came in, because you may need to send copies with your Medigap application.

How insurers price Medigap premiums

Each company decides how to price its policies, and the method affects what you pay now and later. CMS describes three ways:

• Community-rated (no-age-rated): generally the same premium for everyone, regardless of age or gender. Premiums can rise with inflation and other factors, but not because of your age.
• Issue-age-rated (entry-age-rated): based on your age when you buy. Premiums are lower for people who buy younger and do not go up as you age, though they can rise for inflation and other reasons.
• Attained-age-rated: based on your current age, so the premium goes up as you get older. These may be the least expensive at first but can eventually become the most expensive.

The booklet illustrates with sample numbers that it says are not actual costs. Under community rating, a 65-year-old and a 72-year-old buying the same policy both pay $165 a month. Under issue-age rating, the 65-year-old pays $145 and the 72-year-old $175, and those amounts do not rise with age. Under attained-age rating, a 65-year-old starts at $120, then pays $126 at 66 and $132 at 67, rising each year.

Other things can change your price: where you live, medical underwriting if you have no guaranteed right, and discounts some companies offer, for example for women, non-smokers or married people, for paying yearly or by electronic funds transfer, or for multiple policies. Medicare SELECT policies, which require you to use hospitals (and sometimes doctors) in a network for full benefits except in emergencies, generally cost less. Medicare will still pay its share wherever you go. If you buy SELECT, the handbook says you have 12 months to change your mind and switch to standard Medigap. Some states also limit Medigap premium costs.

Shopping for a policy, step by step

The CMS booklet lays out four steps. First, decide which plan letter you want, keeping in mind your current and future health needs and that you might not be able to switch later. Second, find companies selling that plan in your state; Medicare.gov lists them, and your State Health Insurance Assistance Program (SHIP) offers free counseling and may have a Medigap rate comparison guide for your state. Third, get official quotes from more than one company. Fourth, apply.

CMS suggests asking each company these questions:

• Are you licensed in my state? If not, stop and try another company.
• Do you sell the plan letter I want, and a Medicare SELECT or high-deductible version if I am interested?
• Do you use medical underwriting for this policy? (It does not apply during open enrollment or with a guaranteed issue right.)
• Do you have a waiting period for pre-existing conditions, and how long is it?
• Is this policy community-rated, issue-age-rated or attained-age-rated?
• What would my premium be at my age, and how often does it rise because of age?
• Has the premium increased in the last 3 years because of inflation or other reasons, and by how much?
• Do you offer any discounts or additional benefits?

When you apply, fill out the application carefully and answer any medical questions. If you are in your open enrollment period or prove a guaranteed issue right, the company cannot use those answers to deny you or change your price. The company must give you a clearly worded summary of the policy. Pay the insurance company directly, never the agent. Policies generally begin the first day of the month after you apply. If 30 days pass without your policy materials, call the company; after 60 days, call your State Insurance Department.

Illegal sales practices to watch for

CMS lists practices that are illegal when someone sells Medigap. It is illegal to pressure you or lie to get you to switch companies or policies, or to sell you a Medigap policy if the seller knows you already have one (unless you state in writing that you will cancel it), you have Medicaid (except in limited situations), or you are in a Medicare Advantage Plan and not switching back to Original Medicare. It is also illegal to claim a Medigap policy is part of Medicare or another federal program, to say a Medicare Advantage Plan is a Medigap policy, to claim to be a Medicare representative while working for an insurance company, to suggest the federal government approved or recommends a policy, to sell you a Medicare Advantage Plan when you said you want Original Medicare and Medigap, or to ask about your family history or require a genetic test.

If you believe a federal law has been broken, CMS points you to the Inspector General's hotline at 1-800-HHS-TIPS (1-800-447-8477); TTY users can call 1-800-377-4950. Your State Insurance Department handles other insurance problems.

If you already have a Medigap policy

Renewal and when you can be dropped

Standardized Medigap policies bought after 1992 are guaranteed renewable, even if you have health problems. The company can drop you only if you stop paying the premium, you were not truthful on the application, or the company goes bankrupt or out of business. You can generally keep your policy if you move, as long as you still have Original Medicare.

Switching policies

In most cases federal law gives you no right to switch Medigap policies unless you are in your open enrollment period or have a guaranteed issue right. If your state or a company allows it, compare benefits and premiums first, and do not cancel your old policy until you have decided to keep the new one. You get a 30-day free look period with the new policy, and you pay both premiums for the month you have both. Once you cancel an old policy, you cannot get it back, and a policy bought before June 1, 2010 may include coverage newer policies do not.

Switching can also restart a pre-existing condition wait. If you have had your current policy less than 6 months, the new policy may make you wait up to 6 months, minus the months you already had coverage. CMS's example: with 2 months of creditable coverage, the new policy will not cover the condition for another 4 months. After more than 6 months with the same benefits, the new company cannot make you wait. Any benefit the new policy has that your old one did not may carry a wait of up to 6 months either way.

Joining a Medicare Advantage Plan

You can legally keep a Medigap policy after joining a Medicare Advantage Plan, but it would no longer pay anything that supplements Medicare, so you would be paying for coverage you cannot use. If you drop it, you may not be able to get the same policy, or in some cases any policy, back unless you leave during your trial period. Our Original Medicare vs Medicare Advantage guide walks through that choice.

Older policies with drug coverage

If you have an older Medigap policy that includes drug coverage, you can still join a Medicare drug plan, but you cannot have both. If you join, you must tell the Medigap company to remove the drug coverage and adjust your premium, and you cannot add it back. The company must send a notice each year saying whether its drug coverage is creditable. If it is, you avoid the Part D late enrollment penalty as long as you do not go 63 or more days in a row without creditable drug coverage. If it is not, you will probably pay a penalty that, in general, lasts as long as you have Part D. You can join a Medicare drug plan between October 15 and December 7, with coverage starting January 1.

Massachusetts, Minnesota and Wisconsin

These three states standardize Medigap differently from the lettered plans. Massachusetts offers a Core Plan and Supplement 1A Plan (Supplement 1, which covers the Part B deductible, is closed to people new to Medicare since January 1, 2020). Minnesota offers Basic and Extended Basic plans with optional riders, plus Minnesota versions of Plans K, L, M and N. Wisconsin has one basic plan with optional riders, along with 50% and 25% cost-sharing plans similar to Plans K and L and a high-deductible plan ($2,950 in 2026). For details, call the State Insurance Department: Massachusetts 1-877-563-4467, Minnesota 1-800-657-3602, Wisconsin 1-800-236-8517.

Where to get help

• Your SHIP gives free, personalized counseling; find yours at shiphelp.org.
• Your State Insurance Department answers questions about policies and rights in your state, and handles complaints.
• Medicare.gov/medigap-supplemental-insurance-plans lists the companies selling Medigap where you live.
• 1-800-MEDICARE (1-800-633-4227) is open 24 hours a day, 7 days a week; TTY users can call 1-877-486-2048.

If paying Medicare premiums at all is a strain, look at the Medicare Savings Programs before buying more coverage: they are state programs that can pay your Part B premium, and some also pay deductibles and coinsurance.