Medigap: The Complete Guide (2026)

What Medigap Actually Is

Medicare Supplement Insurance, almost always called Medigap, is a private policy you buy to cover the out-of-pocket costs Original Medicare leaves you with. Medicare pays its share of the approved amount for a covered service, and then your Medigap policy pays its share of what is left.

Three structural facts shape everything else on this page.

Medigap only works with Original Medicare. You generally need both Part A and Part B to buy a policy. It is not an alternative to Medicare and it is not a Medicare Advantage plan. Insurance companies generally cannot sell you a Medigap policy if you have coverage through a Medicare Advantage plan or Medicaid.

A policy covers one person. If you and your spouse both want Medigap coverage, you each buy your own policy, and each of you has your own enrollment window tied to your own Part B date and your own 65th birthday.

The plans are standardized and the prices are not. In most states the plans are named by letters, and every plan with the same letter offers the same basic benefits no matter where you live or which company sells it. Price is the only difference between two policies with the same letter. That single fact is why comparison shopping matters more here than in almost any other insurance market.

Any Medigap policy issued since 1992 is guaranteed renewable. The insurer cannot cancel it because your health got worse or because you filed claims. It can only drop you for not paying the premium, for not being truthful on the application, or if the company goes bankrupt or out of business. Guaranteed renewable protects your coverage, not your price. Premiums still rise.

What Each Plan Covers

Ten lettered plans are currently sold in most states: A, B, C, D, F, G, K, L, M and N. Every company that sells Medigap at all must offer Plan A. Beyond that, each company decides which letters it wants to sell, and not every plan is offered in every state.

Scroll the table sideways to see all ten plans.

*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.

A few things in that grid are worth pulling out, because they are where the real decisions live.

Plans K and L work differently from the rest. Instead of covering benefits in full, they cover a percentage and give you an annual out-of-pocket limit. Once you hit that limit and your Part B deductible, the plan pays 100% of covered services for the rest of the calendar year. Those limits are indexed and CMS announces new amounts each autumn, so the 2026 figures above will change.

Plan M is the odd one. It covers everything Plan D covers, but pays only half the Part A deductible.

Only F and G cover Part B excess charges. That matters if your doctors do not accept Medicare assignment, and matters not at all if they do.

High-deductible F and G

Plans F and G also come in high-deductible versions in some states. The benefits are identical to the standard version, but the policy pays nothing until you have absorbed a set amount of Medicare cost-sharing yourself. For 2026 that amount is $2,950, and there is a separate $250 annual deductible for foreign travel emergency care on top of it. The deductible is indexed to inflation and announced each autumn, so treat the figure as current rather than permanent.

High-deductible G is available to anyone. High-deductible F carries the same eligibility restriction as standard F, explained next.

Plans C and F, and Who Cannot Buy Them

Medigap policies sold to people new to Medicare on or after January 1, 2020 are not allowed to cover the Part B deductible. Plans C and F are the only two standardized plans that cover it. The rule did not target those plans directly, it eliminated the benefit that defines them, which closed both letters to that group.

Three details decide whether this applies to you.

Eligibility date governs, not enrollment date. You are considered new to Medicare if you turned 65 on or after January 1, 2020 and get Part A on or after that date. If you were eligible before the cutoff but have not enrolled yet, you may still be able to buy Plan C or Plan F.

If you already have one, you keep it. Existing Plan C and Plan F policies stay in force and stay guaranteed renewable.

Plans D and G are the designated replacements. People new to Medicare on or after the cutoff have the right to buy Plan D or Plan G instead, which give the same benefits except for the Part B deductible.

Two other vintage rules turn up in older policies. 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. And Plans E, H, I and J are no longer sold, though anyone who already has one can generally keep it.

What Medigap Doesn't Cover

Medigap fills gaps in Original Medicare. It does not add benefits Medicare never had. Policies generally do not cover:

• Long-term care, including non-skilled nursing home care
• Vision or dental care
• Hearing aids
• Glasses
• Private-duty nursing

Prescription drugs are the one that surprises people. Medigap policies sold after 2005 do not include drug coverage. If you want it, you join a separate Medicare drug plan. Some older policies still carry a drug benefit, and there are rules about what happens to it if you join a Medicare drug plan, covered further down.

It is also worth naming what is not a Medigap policy, since the names blur together. Medicare Advantage plans, Medicare drug plans, Medicaid, employer or union group health plans including retiree and COBRA coverage, TRICARE, veterans' benefits, long-term care insurance, and Indian Health Service plans are all different things with different rules.

Your 6-Month Open Enrollment Window

This is the most consequential and least understood rule in Medigap, so it is worth being precise.

Your Medigap open enrollment period runs 6 months and starts the first month you have Medicare Part B and you are 65 or older. Both conditions have to be true, so whichever one happens later is what starts the clock. It is a one-time period. It does not repeat every year, it cannot be changed, and nothing you file reopens it.

During that window, an insurance company:

• Must sell you any Medigap policy it offers in your state
• Cannot use medical underwriting to decide whether to accept you
• Cannot deny you coverage because of pre-existing health problems
• Cannot charge you more because you have health problems

That is a genuinely strong set of protections, and it is available exactly once.

Why delaying Part B moves the window

If you or your spouse are still working and you have group health coverage based on that current employment, you may reasonably delay Part B. Your Medigap window does not begin until you enroll in Part B, which means it waits for you rather than expiring while you work. When the employer coverage ends, you get a chance to sign up for Part B without a late enrollment penalty, and your Medigap window starts then.

That is the useful version of this rule. The costly version is signing up for Part B at 65 out of habit while you still have good employer coverage, burning the 6 months on a policy you do not need yet, and arriving at actual retirement with no window left. Age 65 triggers several unrelated clocks at once, which the retirement rules by age guide lays out side by side.

What happens if you miss it

Outside your open enrollment period and outside a guaranteed issue right, insurers may use medical underwriting. In practice that means three things: you may pay more, fewer plans may be available to you, and there is no guarantee any company will sell you a policy at all. They may deny you.

The Pre-Existing Condition Waiting Period

Here is the part that catches even careful readers. Your open enrollment window guarantees that you will be sold a policy and guarantees the price. It does not guarantee that the policy starts paying for everything on day one.

An insurer can refuse to cover your out-of-pocket costs for a pre-existing condition for up to 6 months, and it can do this during your open enrollment period. After 6 months, the policy covers the condition.

Three rules limit how far that goes.

The look-back period is 6 months. A condition can only be excluded if it was treated or diagnosed within the 6 months before your Medigap coverage starts. Something diagnosed years ago and untouched since is not excludable on this basis.

Creditable coverage shortens or eliminates it. If you had at least 6 months of continuous prior creditable coverage, the insurer cannot make you wait at all. Fewer than 6 months still counts proportionally: the insurer subtracts the months you had from the waiting period. Two months of prior coverage leaves a 4-month wait. Most health coverage you recently held can count, but only if your break in coverage was no more than 63 days.

Original Medicare still pays. During any waiting period, Medicare continues covering the condition for Medicare-covered services. What you lose is the Medigap policy's help with your coinsurance and copayments, not the underlying coverage.

Guaranteed Issue Rights

Guaranteed issue rights, also called Medigap protections, are your rights to buy certain Medigap policies in specific situations outside your open enrollment period. In these situations an insurance company must sell you a policy, must cover all your pre-existing conditions, and cannot charge you more because of past or present health problems.

Federal law describes seven situations. Note the plan letters carefully, because a guaranteed issue right usually does not mean any plan you want.

Plans C and F are unavailable to people new to Medicare on or after January 1, 2020, who have the right to buy Plan D or G instead. See the Plans C and F section.

Four things to notice

Only one row uses the latest-of-three-dates rule. The employer group health plan row measures the 63 days from the latest of three separate dates, which can push your deadline well past the day coverage actually ended. No other situation works that way. Applying that rule to a Medicare Advantage termination or a bankruptcy will give you the wrong deadline.

COBRA gives you a choice. If you have COBRA coverage, you can either buy a Medigap policy right away or wait until your COBRA coverage ends.

More than one situation can apply at once. When that happens, you can choose whichever guaranteed issue right works best for your circumstances. If one route gives you broader plan choice or a longer window, take that one.

Keep the paperwork. You may need to prove the right exists. Keep copies of letters, notices, emails and claim denials with your name on them showing your coverage was terminated, and keep the postmarked envelope they arrived in as proof of when it was mailed. You may have to send some of it with your application.

Trial Rights, and Why They Differ

Two of the seven guaranteed issue situations are trial rights, and people conflate them constantly. They are not the same right and they do not pay off the same way.

The first-time-enrollee trial right belongs to someone who joined a Medicare Advantage plan or PACE when they were first eligible for Part A at 65, and decides within that first year to move to Original Medicare. The payoff is the broadest guaranteed issue right in federal law: any Medigap policy sold in your state. No letter restriction at all.

The dropped-Medigap trial right belongs to someone who already had a Medigap policy, dropped it to try Medicare Advantage or a Medicare SELECT policy for the first time, and wants back in within a year. The payoff is restoration rather than free choice: you get your old policy back if the same company still sells it, and if not, you fall back to Plans A, B, C, D, F or G.

So the first right rewards someone who never had Medigap and is correcting course at the outset. The second protects someone who had Medigap, experimented, and wants their coverage restored. Both run on a less-than-one-year clock and both share the 60-days-before and 63-days-after window.

Both rows carry a note that your rights may last an extra 12 months under certain circumstances. That is a pointer to state law, not a federal extension, and CMS does not define the circumstances. Your State Insurance Department does.

How Insurers Price Medigap

Every plan with the same letter offers the same benefits, so price is the only real variable. Companies set that price one of three ways, and the difference compounds over decades.

The distinction that gets mangled everywhere is the difference between age and inflation. All three methods can raise your premium for inflation and rising medical costs. None of them is a fixed price. What separates attained-age rating is that it adds a second, independent increase tied to your own aging, on top of the first one.

So a guide or an agent telling you that an issue-age policy "will not go up" is wrong. It will go up. It just will not go up because of your birthday.

This is also why the cheapest quote at 65 is a poor way to choose. An attained-age policy that looks like a bargain in your first year can cost considerably more than a community-rated policy by your late seventies. When you call for quotes, ask which method the company uses, and if it is attained-age, ask how frequently and by how much the premium has increased for people your age.

State Rules Change More Than You Expect

Everything above is federal. States layer their own rules on top, and in several places those rules matter more than the federal baseline. This is also the fastest-moving part of Medigap, so what follows describes the categories rather than trying to keep a list of states current.

Annual switching windows

A growing number of states give you a yearly chance to change Medigap policies without medical underwriting. These are commonly called birthday rules, and grouping them under one name hides how differently they work. Four distinct structures exist:

• Change plan and carrier. Some states let you move to a different company and a different plan letter, usually with equal or lesser benefits.
• Change plan, same carrier. Some states let you change plan letters but only within your current insurer or its affiliates. You cannot shop the market.
• Change carrier, same plan. At least one state runs the mirror image: you can take your Plan G to a cheaper company, but you cannot move from Plan G to Plan N.
• Year-round switching. A few states allow changes at any time rather than in a window, sometimes with the unusual ability to move up in benefits rather than only sideways or down.

The windows themselves vary too. Some start on your birthday, some on the first day of your birth month, and at least one runs from your policy anniversary instead. Lengths range from about 30 days to more than 60. Some states cap eligibility by age. Almost all of them restrict you to equal or lesser benefits, which means these windows are usually a tool for lowering your premium rather than upgrading your coverage.

Pricing restrictions

A minority of states restrict or prohibit attained-age rating, effectively requiring community rating. At least one state made this change recently and applied it only to newly issued policies, which means longtime residents there may still hold older policies priced the old way. If premium growth over time matters to you, this is worth asking your state department about directly.

Additional enrollment rights

Some states provide Medigap open enrollment periods beyond the federal one, including periods for people under 65. Others extend trial rights past the federal window. None of this is visible in the federal rules, and it is the single most common reason someone is told they have no options when they actually do.

Medicare SELECT

In some states you can buy a Medicare SELECT policy, which is a standardized Medigap policy with a provider network attached. You use hospitals, and in some cases doctors, within the network to be eligible for full benefits. These policies generally cost less than comparable Medigap policies.

The trade-off is straightforward. If you use a non-network hospital or doctor for non-emergency services, you pay some or all of what the policy would otherwise have covered. Medicare still pays its share of approved costs no matter which hospital or doctor you choose, so the network restriction affects the supplemental layer rather than your underlying Medicare coverage.

Two rules matter if your situation changes. Moving out of a Medicare SELECT policy's service area is one of the seven guaranteed issue situations. And if you have held the SELECT policy for more than 6 months, you can buy a standardized Medigap policy from your current insurer with the same or fewer benefits without answering medical questions.

Switching Medigap Policies

In most cases federal law gives you no right to switch Medigap policies. The exceptions are the ones already covered: you are inside your 6-month open enrollment period, or you have a guaranteed issue right. Beyond that it depends on your state's rules and on whether an insurer is willing to sell to you, which usually means underwriting.

If you do switch, the mechanics have teeth.

Do not cancel the first policy until you have decided to keep the second. On the application for the new policy you will have to promise you will cancel the old one, but the promise is not the cancellation. You get a 30-day free look period starting when you receive the new policy. You will pay both premiums for the month you hold both.

Once you cancel the old policy, you cannot get it back. This matters most for people holding a plan letter that is no longer sold, or a policy bought before June 1, 2010 that may include coverage unavailable in newer policies.

A new policy can bring a new waiting period, depending on how long you have held the current one. If you have had your current policy for less than 6 months, the new insurer may impose a pre-existing condition waiting period, but must subtract the months you have already had of your current policy or other creditable coverage. If you have held it longer than 6 months and the new policy has the same benefits, the new insurer cannot exclude your pre-existing condition or make you wait. But if the new policy includes a benefit your old one did not have, you may wait up to 6 months for that specific benefit regardless of how long you have been covered.

Moving out of state does not force a change. You can generally keep your current Medigap policy wherever you live, as long as you still have Original Medicare.

Medigap and Medicare Advantage

These are alternatives, not companions. Medigap supplements Original Medicare. Medicare Advantage replaces it as the way you receive your Medicare coverage. You cannot usefully have both.

You do have a legal right to keep a Medigap policy after joining a Medicare Advantage plan, which sounds better than it is. While you are in the Advantage plan the Medigap policy provides no supplemental benefit, and it cannot pay your Advantage plan's deductibles, copayments, coinsurance or premiums. You are paying for coverage you cannot use.

Selling rules follow from that. It is illegal for someone to sell you a Medigap policy knowing you are in a Medicare Advantage plan, unless you are switching back to Original Medicare. It is equally improper for someone to sell you a Medicare Advantage plan after you have said you want to stay in Original Medicare and buy Medigap.

The sequencing detail worth knowing: if you have a Medicare Advantage plan and plan to return to Original Medicare, you can apply for a Medigap policy before your Advantage coverage ends. Ask that the new policy start when your Advantage enrollment ends, so you have continuous coverage. Applying first and timing the start date is the difference between a clean transition and a gap.

Medigap and Medicare Drug Coverage

Medigap policies sold after 2005 do not include prescription drug coverage. If you want it, you join a separate Medicare drug plan, and the annual window for that runs October 15 to December 7 with coverage starting January 1.

If you hold an older Medigap policy that does include drug coverage, several rules apply at once.

You can still join a Medicare drug plan. If you do, you must tell your Medigap insurer, who will remove the drug coverage from your policy and adjust your premium. You cannot add it back afterward.

Whether you face a late enrollment penalty depends on whether your Medigap drug coverage was creditable, meaning it was expected to pay at least as much as standard Medicare drug coverage. If it was creditable, you avoid the penalty as long as you do not go 63 or more days in a row without creditable drug coverage. Do not drop the Medigap drug coverage before your new plan starts. If it was not creditable, you will probably owe a late enrollment penalty that grows for each month you waited, and generally lasts as long as you have Part D.

Your Medigap insurer must send you a notice each year telling you whether the drug coverage is creditable, and must tell you if that status changes. Those notices are the evidence, so keep them.

Medigap Under 65: Disability and ESRD

You may qualify for Medicare before 65 because of a disability, End-Stage Renal Disease, or ALS. Medigap access for that group is the biggest gap between what people expect and what the law provides.

Federal law generally does not require insurance companies to sell Medigap policies to people under 65. That is the whole federal rule. Everything beyond it is state law.

Roughly two-thirds of states do require insurers to offer at least one kind of Medigap policy to people with Medicare under 65. The composition of that list changes, and more importantly, the rights differ underneath it: some states extend them to everyone under 65 with Medicare, while others extend them only to people eligible because of disability or ESRD. Which plans are available and what they cost also varies. Your State Insurance Department is the place to settle this.

Even in states without a requirement, some insurers voluntarily sell to people under 65. Expect higher prices than people over 65 pay and expect medical underwriting. Some of the federal guaranteed issue rights are available to people under 65 as well.

Massachusetts, Minnesota, and Wisconsin

These three states standardize Medigap differently and do not use the lettered system. If you live in one of them, the benefit grid earlier in this guide does not describe your options, although the enrollment windows, guaranteed issue rights and pricing concepts still broadly apply.

Massachusetts

Three plans: a Core Plan, a Supplement 1 Plan, and a Supplement 1A Plan. Basic benefits include Part A coinsurance plus 365 additional days after Medicare coverage ends, Part B coinsurance, the first 3 pints of blood each year, and hospice coinsurance. The higher plans add the Part A deductible, skilled nursing facility coinsurance, foreign travel emergency and more inpatient mental health days. Supplement 1, which covers the Part B deductible, is closed to people new to Medicare on or after January 1, 2020, on the same logic that closed Plans C and F elsewhere.

Minnesota

A Basic Plan and an Extended Basic Plan, with riders you add to design the coverage you want. Minnesota's basic benefits are broader than the federal baseline, including home health services cost sharing under both Parts A and B, and hospice and respite cost sharing. Riders cover the Part A deductible, the Part B deductible, usual and customary fees, and preventive care Medicare does not cover. Minnesota versions of Plans K, L, M and N are also available.

Wisconsin

One base plan with optional riders. The basic plan covers Part A and Part B coinsurance, 3 pints of blood, hospice coinsurance, skilled nursing facility coinsurance, 175 lifetime days of inpatient mental health beyond what Medicare covers, and 40 home health visits per year beyond Medicare. Riders add the Part A deductible, a 50% Part A deductible option, additional home health care, the Part B deductible, Part B excess charges, foreign travel emergency, and Part B copayment or coinsurance. Cost-sharing plans similar to Plans K and L exist, as does a high-deductible option.

Common Mistakes

Treating the fall Medicare window as a Medigap window. October 15 to December 7 governs drug plans and Medicare Advantage. It does nothing for Medigap. Neither does the Medicare Advantage open enrollment period in the new year.

Signing up for Part B at 65 while still covered at work. This starts a 6-month clock you cannot restart, on a policy you may not need for years.

Assuming open enrollment means immediate full coverage. The pre-existing condition waiting period survives your open enrollment window. It does not survive a guaranteed issue right.

Assuming a guaranteed issue right means any plan. Six of the seven situations limit you to Plans A, B, C, D, F or G. Only the first-time-enrollee trial right opens the full menu.

Applying the latest-of-three-dates rule to the wrong situation. It appears in exactly one row, the employer coverage row. Everywhere else the 63 days runs from when coverage ended.

Dropping Medigap to try Medicare Advantage without checking the trial right first. Reversal is possible only inside a narrow window and only the first time.

Cancelling the old policy before the free look period ends. You get 30 days. Once the old one is gone it is gone, which matters most for discontinued plan letters and pre-2010 policies.

Buying on the first-year price. An attained-age policy that is cheapest at 65 can be the most expensive at 78. Ask which pricing method the company uses.

Comparing different plan letters across companies. Plan G from one company and Plan G from another are identical in benefits. Compare like for like, then compare on price and rate history.

Assuming one policy covers a couple. It covers one person. Two people need two policies and each has their own window.

FAQ

Related Knowledge Blasts

Short, plain-language breakdowns of the rules behind this guide:

When You Can Buy Medigap Without Medical Underwriting →

Why Your Medigap Premium Keeps Rising, and Whether You Can Switch →

How the Medicare Advantage Trial Right Works →

The January to March Window to Leave Medicare Advantage →

The Letter That Proves You Do Not Owe a Medicare Drug Penalty →

Does Your Coverage Count as Creditable Drug Coverage? →

The Medicare Penalty That Costs 10 Percent for Every Year You Wait →

The Medicare Part B Special Enrollment Period When Employer Coverage Ends →