Medigap Plans Explained: Plan G vs Plan N (2026)

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 has no annual limit. 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 for most people, which plans are closed to newer enrollees, and the one six-month window when you can buy any plan regardless of your health.1

Why do you need Medigap?

Original Medicare has no annual out-of-pocket limit. 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. Part A adds a hospital deductible of $1,736 per benefit period, and that deductible can apply more than once in a year. A serious illness can produce bills with no upper bound.1

Medigap closes that exposure. It pays some or all of those deductibles and coinsurance amounts, which makes your yearly costs predictable. It works only alongside Original Medicare, not with a Medicare Advantage plan, and each policy covers one person. A married couple who both want coverage need two separate policies.

If you are choosing coverage today, two decisions carry the most weight. The first is Plan G versus Plan N: Plan G costs more but leaves you owing only the annual Part B deductible, while Plan N trades a lower premium for small office and emergency-room copays. The second is timing: buy during your six-month Medigap Open Enrollment Period, because once it closes, most states let an insurer underwrite your application, raise your rate for a health condition, or turn you down. The rest of this guide explains how the lettered plans work and how those two choices play out.

Does every insurer cover the same thing?

In most states, 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 insurer covers, per the Medicare.gov plan-benefit comparison. The companies compete on price, customer service, and rate stability, not on what the plan pays.2

Three states are the exception. Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans under their own systems rather than the federal A-through-N letters, so the rest of this guide describes the lettered plans used in the other 47 states and the District of Columbia.

Because the benefits are fixed, two quotes for the same letter differ only on price and on how each insurer prices its policies. That makes the letter the first decision and the insurer the second.

The plans most people pick: Plan G and Plan N

For someone newly eligible for Medicare, the practical choice narrows to two plans. Plan G is the most complete plan still available to people who became eligible on or after January 1, 2020. It covers everything Original Medicare leaves open 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 Part B deductible for the year, a Plan G holder generally has no further cost-sharing on Medicare-covered services.

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 that don't lead to an inpatient admission. Plan N also does not cover Part B excess charges, the amount a provider who doesn't accept Medicare assignment can bill above the approved rate. In exchange, Plan N premiums are usually lower than Plan G premiums.2

A third option suits people who want catastrophic protection at the lowest premium. High-deductible Plan G 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 starts paying. The premium is much lower, and the plan is built for people willing to absorb routine costs in exchange for a hard cap once that deductible is met.2

Plans C and F are closed to newer enrollees

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. Under the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA), any Medigap plan that pays the Part B deductible is closed to people who first became eligible for Medicare on or after January 1, 2020, confirmed by the Centers for Medicare and Medicaid Services.

The closure works by eligibility date, not purchase date. If you became eligible for Medicare before January 1, 2020, you can still buy or keep Plan C or Plan F. If you became eligible on or after that date, those two plans are off the table, which is why Plan G has become the default top-tier choice for newer enrollees: it's identical to Plan F except that you pay the one Part B deductible yourself.3

The Medigap Open Enrollment Period

The single most important timing rule in Medigap is the Medigap Open Enrollment Period. It's 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 those six months, the guaranteed-issue rules require insurers to sell you any Medigap policy they offer at their best available rate, regardless of your health history, with no medical underwriting.3

Outside that window, the protection mostly disappears. In most states, an insurer can require medical underwriting, charge a higher rate based on your health, or decline to sell you a policy at all. A few states extend guaranteed-issue rights more broadly or allow yearly switching, so your state's rules matter, but the federal floor is that one six-month period.

This is why the choice between Plan G and Plan N is best made during open enrollment. If you start on Plan N to save on premiums and later want to move up to Plan G, that later switch can trigger underwriting once your open enrollment 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 have passed laws giving Medigap policyholders an annual window to switch plans without medical underwriting, commonly called "birthday rules." These exist on top of the federal six-month open-enrollment period and apply whether or not you already used your federal OEP. If you live in one of these states, you're not locked in for life.2

Notes: The New Mexico rule (SB 21) takes effect January 1, 2027 and is not yet in force. Most birthday-rule states, including California, limit the switch to a plan of equal or lesser benefits. Massachusetts, Minnesota, and Wisconsin use their own non-standardized plan structures and operate under separate state frameworks. Louisiana's birthday rule is narrower than most: it limits the switch to your current insurer or one of its affiliates, not any insurer in the state (see Louisiana's Medigap birthday rule). Two states use a different annual mechanism entirely: Missouri ties its guaranteed-issue window to your policy's anniversary date rather than your birthday (see Missouri's Medigap anniversary rule), and Maine offers year-round guaranteed-issue protections, including an annual Plan A month from every insurer (see Maine's Medigap guaranteed-issue rules).4,3

Outside these states the federal rule applies: underwriting is generally available after your one-time six-month OEP closes.

How much does Medigap cost?

Medigap premiums vary widely, and there is no single national price. The benefits inside a letter are fixed, but the price is not: it depends on the insurer, your state, your age, and in many states your gender and tobacco use. Because carriers set the premiums rather than Medicare, two policies with identical benefits can be priced very differently, so the only reliable way to learn your own cost is to compare quotes for the same plan letter across the insurers selling it in your state.1

Insurers also use one of three pricing methods, which shapes how your premium changes as you age:

• Community-rated policies charge everyone the same premium regardless of age.
• Issue-age-rated policies base your premium on your age when you buy, and that starting point doesn't rise simply because you get older.
• Attained-age-rated policies start lower but increase as you age, so a low first-year quote can climb over time.

Two quotes for the same Plan G can therefore diverge sharply over a decade based on pricing method alone. When you compare policies, ask which method each insurer uses, not just the first-year premium. Remember that Medigap does not include prescription drug coverage; you add a separate Part D plan for that.

For free, unbiased help comparing quotes and confirming your guaranteed-issue window, contact your State Health Insurance Assistance Program (SHIP), the federally funded Medicare counseling service in every state, or call Medicare directly at 1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048). SHIP counselors do not sell policies and can walk you through your state's specific switching rules.

Medigap vs. Medicare Advantage

Medigap and Medicare Advantage are mutually exclusive. Medigap supplements Original Medicare and pays its cost-sharing; Medicare Advantage replaces Original Medicare with a private plan that has its own network and out-of-pocket cap. You can't hold both, and you generally can't use a Medigap policy to pay costs under an Advantage plan.

The basic tradeoff: Original Medicare plus Medigap lets you see any provider in the country that accepts Medicare, with predictable costs and no prior authorization, but you pay a monthly Medigap premium and buy Part D separately. Medicare Advantage often has a low or $0 plan premium and bundles drug coverage, but limits you to a network and uses prior authorization. For a fuller comparison, see the Medicare overview linked below.1

Medigap Pricing and Switching Rules by State

Medigap benefit letters are federally standardized, so a Plan G covers the same things in every state. What varies is the price and your switching rights: what insurers charge differs sharply by state, and a handful of states add birthday or guaranteed-issue rules that let you change plans without underwriting. Your state guide covers the pricing and switching rules where you live.

Learn More

Find personalized 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.