Original Medicare leaves your costs open-ended, and Medigap (Medicare Supplement Insurance) is how you cap them. It's a private policy that pays the deductibles and coinsurance you'd otherwise owe yourself, including the 20% Part B coinsurance that Original Medicare never caps. The policies are standardized into lettered plans, so the same letter buys the same benefits from every insurer. This guide explains how the letters work, why Plan G and Plan N are the real choice, which plans are closed to people new to Medicare, and when you can buy regardless of your health.,

Why do you need Medigap?

Original Medicare sets no yearly limit on what you pay out of pocket unless you have supplemental coverage, such as Medigap, Medicaid, or employer, retiree, or union coverage. Without one, the exposure is open-ended: after the Part B deductible ($283 in 2026) you pay 20% of the Medicare-approved amount for most outpatient care, with no ceiling on how high that 20% can run, and Part A adds a $1,736 hospital deductible per benefit period that can apply more than once a year.

Medigap closes that exposure: it pays some or all of those deductibles and coinsurance, making your yearly costs predictable. It works only alongside Original Medicare, and while you're in a Medicare Advantage plan CMS says it's illegal for anyone to sell you a Medigap policy unless you're switching back. Each policy covers one person, so a couple who both want coverage need two policies.

Does every insurer cover the same thing?

Outside Massachusetts, Minnesota, and Wisconsin, Medigap is sold as 10 lettered plans: A, B, C, D, F, G, K, L, M, and N. The benefits inside each letter are set by federal rule, so a Plan G from one insurer covers exactly what a Plan G from another covers, per the Medicare.gov plan-benefit comparison. Insurers compete on price, service, and rate stability, not on what the plan pays.

Those three states standardize their plans under their own systems, so the rest of this guide describes the lettered plans used in the other 47 states and DC. Either way, the letter is your first decision and the insurer your second.

The plans most people pick: Plan G and Plan N

For someone newly eligible, the practical choice narrows to two plans. Plan G is open to everyone, including people new to Medicare after Plans C and F closed. It covers the same benefits as Plan F except the annual Part B deductible: the Part A hospital deductible, Part A and Part B coinsurance, skilled nursing facility coinsurance, and Part B excess charges. After you pay that one deductible for the year, you generally have no further cost-sharing on Medicare-covered services in the United States. Foreign travel emergency care is the exception, covered at 80% up to plan limits.

Plan N covers the same major gaps but shifts a little cost back to you. It pays 100% of the Part B coinsurance except for a copay of up to $20 for some office visits and up to $50 for emergency-room visits. The insurer must waive that ER copay if the visit leads to an admission paid under a Medicare Part A inpatient stay, so a visit that ends in observation status rather than a Part A admission can still cost you the $50. Plan N also does not cover Part B excess charges, what a provider who doesn't accept Medicare assignment can bill above the approved rate. Its premiums are usually lower than Plan G's.

High-deductible Plan G, a third option, trades routine costs for a hard cap. It is offered in some states, not everywhere, so check whether an insurer sells it where you live. Where offered, it carries the same benefits as standard Plan G, but you pay Medicare-covered costs up to a deductible of $2,950 in 2026 before the policy pays, plus a separate $250-per-year deductible for foreign travel emergency care. The premium is much lower in exchange.

Feature Plan G Plan N High-deductible Plan G (where offered)
Part A hospital deductible Covered Covered Covered after the $2,950 deductible
Part B coinsurance Covered in full Covered, minus up to $20 office / $50 ER copays Covered after the $2,950 deductible
Part B excess charges Covered Not covered Covered after the $2,950 deductible
Annual Part B deductible You pay it You pay it Counts toward the $2,950 deductible

Plans C and F are closed if you became eligible for Medicare in 2020 or later

Plans C and F once covered the annual Part B deductible on top of the other gaps, which made Plan F the most complete plan on the market. The Medicare Access and CHIP Reauthorization Act of 2015 (MACRA) prohibits the sale of any Medigap policy covering the Part B deductible to people newly eligible for Medicare on or after January 1, 2020, as CMS confirms.

The closure works by eligibility date, not purchase date, and the federal test has two parts: CMS treats you as new to Medicare only if you turned 65 on or after January 1, 2020 and you get Part A on or after that date. Because both must be true, two groups reaching 65 today fall outside the closure and may still be able to buy Plan C or Plan F: someone eligible for Medicare before January 1, 2020 who has not yet enrolled, and someone who already had Part A before then because of a disability or End-Stage Renal Disease and is only now aging in at 65.

If you are new to Medicare, you are not left without a route: CMS says you have the right to buy Plans D and G instead, which give the same benefits but don't cover the Part B deductible. And if you already hold a Plan C or Plan F, you don't have to give it up. Any Medigap policy issued since 1992 is guaranteed renewable, so the insurer can't cancel it while you stay enrolled and pay the premium.

The Medigap Open Enrollment Period

The most important timing rule is the Medigap Open Enrollment Period: a one-time, six-month window that begins the first month you're both age 65 or older and enrolled in Medicare Part B. During it, federal rules require insurers to sell you any Medigap policy they offer regardless of your health history, with no medical underwriting, and they can't charge you more because you have health problems. One limit survives inside the window: an insurer may still refuse to cover your out-of-pocket costs for a pre-existing condition for up to six months, unless you had at least six months of continuous creditable coverage beforehand. A guaranteed issue right is stronger on this point, requiring the insurer to cover all your pre-existing conditions with no waiting period.

Outside that window the protection narrows, but it does not vanish. Federal guaranteed-issue rights cover an enumerated set of situations rather than a standing right to buy whenever you want one: an employer, retiree, COBRA, or union plan that pays after Medicare ending; a Medicare Advantage plan leaving Medicare or your area, or your move out of its service area; your Medigap insurer going bankrupt; and the two trial rights. In one of those, an insurer must sell you a policy, cover all your pre-existing conditions, and not charge you more for past or present health problems. Each carries its own deadline, generally 63 days after your other coverage ends, and its own restricted list of letters, usually Plan A, B, C, D, F, or G rather than any plan sold. If none fits, and unless your state adds a rule, an insurer can require medical underwriting, charge a higher rate for your health, or decline to sell you a policy. A few states extend guaranteed-issue rights more broadly or allow yearly switching, so your state's rules matter.

This is why the Plan G versus Plan N choice is best made during open enrollment: moving up later can trigger underwriting once the window has closed, and a health condition could make the move expensive or impossible.

State birthday rules: annual Medigap switching rights

A handful of states give Medigap policyholders an annual window to switch plans without medical underwriting, commonly called "birthday rules." They exist on top of the federal six-month open-enrollment period and apply whether or not you already used it.

State Window Plans you can switch to Same or any insurer Age limit
California 60 days from birthday Equal or lesser benefits Not stated by the state None stated
Illinois 45 days from birthday Equal or lesser only Same issuer or an affiliate Ages 65–75
Maryland Birthday plus the 30 days after Equal or lesser Any insurer None
Virginia 60+ days from birthday Same benefits Any insurer None
New Mexico 60 days from birthday month Equal or lesser Not stated by the state Age 65+
Washington Year-round (no birthday window) Any plan within same tier (B–N to B–N, or A to A) Not stated by the state None
Idaho 63 days from birthday Similar or lesser benefits Any Idaho insurer None
Nevada 60+ days from first of birthday month Equal or lesser benefits Any insurer None
Louisiana 63 days from birthday Equal or lesser benefits Same insurer or affiliate only None
Oklahoma 60+ days from birthday Equal or lesser benefits Same or any carrier None
Kentucky Within 60 days of birthday Same plan letter only Different insurer None
Delaware 30 days before to at least 30 after birthday Same or lesser benefits Current or different carrier None
Indiana 1 month before to 1 month after birthday Same plan letter only Different carrier 65+
West Virginia 60 days from first of birthday month, but only if your policy is already 24 months old Same or lesser benefits Same insurer or affiliate only None stated

Notes: West Virginia's rule (W. Va. Code § 33-15F-1, from 2026 House Bill 4869) reaches policies delivered, issued, reissued, or extended in the state on or after June 1, 2026, and picks up an older policy at its next term change or premium adjustment. New Mexico's rule (SB 21) takes effect January 1, 2027 and is not yet in force. Illinois, Louisiana, and West Virginia confine the switch to your own insurer or an affiliate (see Louisiana's rule). New Mexico and Washington don't state whether you may move to a different company, so confirm that with your state insurance department. California's advisory is silent on that point, but California law is not: the statute lets you buy the replacement from your current insurer or a different one (see California's rule). The list isn't exhaustive: Oregon has a birthday rule whose terms aren't documented here, and Connecticut, Maine, Massachusetts, Missouri, New York, Rhode Island, and Washington grant similar annual rights under their own rules. Two states use a different mechanism: Missouri ties its window to your policy's anniversary rather than your birthday (see Missouri's anniversary rule), and Maine offers year-round guaranteed-issue protections, including an annual Plan A month from every insurer (see Maine's rules).,

Conditions the table can't hold. West Virginia's window is annual on its face, but the right applies only if the policy has been in force for at least 24 months when the replacement takes effect, and every replacement restarts that clock, so a West Virginian can use it about every other year at best. A policy reissued or assumed by the same insurer or an affiliate without a gap still counts. The replacement must come from that insurer or an affiliate and offer the same or lesser benefits; if neither has accepted applications for a same-or-lesser plan for 12 months, you may buy from any insurer authorized in the state, but the 24 months still applies and a richer letter is still barred. The same section carries a far wider right that is not a birthday rule at all: someone 65 or older entitled to Medicare who loses Medicaid, including partial dual eligibility, gets 63 days to buy any Medigap policy actively offered to new enrollees by any authorized insurer, with no underwriting and no pre-existing condition exclusion, whether or not they ever held Medigap. In Maryland, a policyholder underwritten and given less than the preferred rate is entitled to the preferred rate during the guaranteed-issue period, so the window can lower your price and not only change your carrier. Nevada's rule does not let you re-enroll with the same company in the same plan to move off a rated-up premium, and it reaches only Nevada residents: someone who bought out of state and now lives in Nevada, and expressly not someone who bought in Nevada and has since moved away. If you bought in Virginia and moved away you still get Virginia's birthday-rule notice, but the State Corporation Commission warns that the law of the state you now live in governs the purchase and you may be underwritten.

If you're under 65 and on Medicare because of a disability, read the table more carefully. Oklahoma's rule reaches you, but the Oklahoma Insurance Department says carriers need only offer disability enrollees one of the ten standardized plans during their open enrollment period, so your choice of letters can be far narrower. Idaho no longer lets insurers rate new Medigap policies by age, but that ban does not reach you either: the Idaho Department of Insurance says people eligible for Medicare for reasons other than age may be charged up to 150% more, with the premium changing to the age-based rate at 65. Kentucky's birthday-rule law also created a six-month open enrollment period for people under 65 newly eligible for Medicare; during it every Medigap policy sold in the state must be available to them, they may not be charged more than the weighted average aged premium rate, and the policy may contain no waiting period and no pre-existing-condition exclusion.

Where the statutes spell it out (Illinois, Virginia, Nevada, and California), the insurer is barred from denying you, conditioning the policy, or discriminating in price because of health status, claims experience, receipt of health care, or a medical condition. That protects you from health underwriting, not from the price itself, which still varies by policy and location and can change each year. So price the policy before you apply.

How much does Medigap cost?

Medigap premiums vary widely, with no single national price. Medicare says a Medigap premium varies based on which policy you buy, where you live, and other factors, and can change each year. CMS names some of those other factors: medical underwriting and discounts, on top of the rating method the insurer uses. The plan letter fixes your benefits, not your bill, so compare quotes for the same letter across insurers in your state. Medigap policies follow state as well as federal law, so your state insurance department or SHIP can confirm what applies where you live.

Insurers also price a policy under one of three rating methods, which shapes how your premium changes as you age:

  • Community-rated (also called no-age-rated) policies generally charge everyone the same premium, regardless of age or gender. The premium can still go up because of inflation and other factors, just not because of your age.
  • Issue-age-rated (also called entry-age-rated) policies base the premium on the age you are when you buy. It can go up because of inflation and other factors, but not because you enter an older age bracket.
  • Attained-age-rated policies base the premium on your current age, so it goes up as you get older. These may be the least expensive at first, but they can eventually become the most expensive.

Two quotes for the same Plan G can diverge sharply over a decade on pricing method alone, so ask which method each insurer uses, not just the first-year premium.

For free help comparing quotes and confirming your guaranteed-issue window, contact your State Health Insurance Assistance Program (SHIP). Medicare's own handbook points beneficiaries to their SHIP for free, personalized, and unbiased health insurance counseling, and SHIP counselors are trained and certified to help with Medicare Supplement coverage specifically, including plan comparison and enrollment., Find your state's program at shiphelp.org or by calling 1-877-839-2675; many states run it under another name, such as HICAP, SHICK, SHINE, or VICAP. No one can be a licensed insurance agent and a SHIP team member at once, so a SHIP counselor has no policy to sell you. Medicare's own helpline is 1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048).

Medigap vs. Medicare Advantage

Medigap and Medicare Advantage are mutually exclusive. Medigap supplements Original Medicare and pays its cost-sharing; Medicare Advantage replaces it with a private plan that has its own network and out-of-pocket cap, and a Medigap policy can't pay that plan's copayments, coinsurance, deductibles, or premiums. That is not a permanent lock-out: if you joined Medicare Advantage for the first time, a federal trial right lets you buy a Medigap policy and a separate Medicare drug plan if you return to Original Medicare within 12 months of joining.

The basic tradeoff: Original Medicare plus Medigap keeps you out of a plan network and away from prior authorization, which Original Medicare generally does not require, but you pay a monthly Medigap premium and buy Part D separately. Medicare Advantage often has a low or $0 plan premium (CMS puts the 2026 average at about $14.00 a month) and bundles drug coverage, but most plans, especially HMOs, require in-network providers and may require prior authorization.

Frequently Asked Questions

What's the difference between Plan G and Plan N?

Both cover the major gaps in Original Medicare. Plan G covers them all except the annual Part B deductible, including Part B excess charges, with no further copays. Plan N costs less but adds copays of up to $20 for some office visits and up to $50 for ER visits, waived when the visit leads to an admission paid as a Part A inpatient stay, and it doesn't cover Part B excess charges.

Why do two insurers charge different prices for the same Medigap plan?

The benefits inside each lettered plan are standardized by federal rule, so a Plan G covers the same things at every insurer. The price is not: it varies by which policy you buy, where you live, and other factors, and can change each year. CMS adds medical underwriting and discounts to that list, alongside the insurer's rating method. Same coverage, different price, so compare quotes.

Can I still buy Plan F?

Only if you first became eligible for Medicare before January 1, 2020. Plans C and F, which cover the Part B deductible, are closed to people new to Medicare on or after that date under MACRA, and the test turns on eligibility, not enrollment: someone eligible before then who has not yet enrolled, and someone who already had Part A before then because of a disability or End-Stage Renal Disease, may still be able to buy one. If you are new to Medicare, you have the right to buy Plan D or Plan G instead; Plan G is identical to Plan F except that you pay the annual Part B deductible yourself.

What happens if I miss my Medigap Open Enrollment Period?

You can still apply, but the blanket protection ends with the window. After it closes, buying without medical underwriting depends on having a federal guaranteed-issue right, which covers enumerated situations such as an employer or union plan ending, a Medicare Advantage plan leaving your area, or a trial right, each with its own deadline (generally 63 days after your other coverage ends) and its own restricted list of plan letters. If none applies and your state supplies no right of its own, insurers can use medical underwriting to charge more based on your health or deny coverage. Some states do offer broader guaranteed-issue rights or annual switching windows, so check your state's rules.

Does Medigap cover prescription drugs?

No. Medigap and drug coverage are separate purchases: on Original Medicare you buy a Medigap policy for cost-sharing and a Medicare drug plan (Part D) for prescriptions.

Medigap Pricing and Switching Rules by State

Pick your state for its Medigap pricing and switching rules.

CaliforniaView guide ConnecticutView guide DelawareView guide IdahoView guide IllinoisView guide IndianaView guide KentuckyView guide LouisianaView guide MaineView guide MarylandView guide MassachusettsView guide MinnesotaView guide MissouriView guide NevadaView guide New YorkView guide OklahomaView guide OregonView guide VirginiaView guide WashingtonView guide WisconsinView guide
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Learn More

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Find help comparing Medigap plans and your guaranteed-issue window at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.

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