Medicare 2026

Medigap Plan Letters Explained: How Plans G, N and the Others Differ

If you're new to Medicare, you've probably noticed that Medigap plans come with letters — A, B, D, G, K, L, M, N, and in some cases C and F. The letters aren't a grading system. They're a federal shorthand for what each plan covers. This guide walks through what those letters mean, which ones are open to new enrollees, and the questions worth asking before you choose.

What a Medigap plan actually does

Medigap — also called Medicare Supplement Insurance — is private insurance that works alongside Original Medicare (Part A hospital and Part B medical). After Medicare pays its share of a covered service, your Medigap plan picks up some or all of the coinsurance, copayments and deductibles that would otherwise come out of your pocket. It does not replace Medicare; it fills gaps in it.

Because federal law standardizes these plans by letter, a Plan G from one insurer provides the same basic benefits as a Plan G from another. The differences between companies come down to price, customer service, how they handle rate increases over time, and extras like household discounts. That standardization is helpful: once you understand what a letter covers, you can compare carriers on an apples-to-apples basis.

One important caveat: Massachusetts, Minnesota and Wisconsin standardize Medigap under their own frameworks and use their own plan names. If you live in one of those states, the letter chart below won't match what you'll see offered.

The letters currently sold to new enrollees

Eight letters are available to people newly eligible for Medicare: A, B, D, G, K, L, M and N. Here's a plain-English sense of how they differ in approach, not in price (premiums vary by insurer, location, age and other factors, so we're staying away from numbers).

• Plan A covers a core set of basics, including Part A hospital coinsurance and Part B coinsurance. It's the slimmest of the standardized options.
• Plan B adds coverage for the Part A deductible on top of the Plan A basics.
• Plan D builds further, adding help with skilled nursing facility coinsurance and the first three pints of blood, among other items.
• Plan G is one of the most comprehensive options available to new enrollees. It covers nearly everything Medicare leaves behind, with one notable exception: it does not cover the Part B deductible, because federal law no longer allows new plans to do so. There is also a high-deductible version of Plan G for people who prefer a lower monthly premium in exchange for paying more out of pocket before coverage kicks in.
• Plan N covers much of what Plan G does, but asks you to pay small copays for some office visits and emergency room trips that don't result in admission, and it does not cover Part B "excess charges" (the extra amount some providers can bill above Medicare's approved amount).
• Plans K and L take a cost-sharing approach: they cover a percentage of certain costs rather than the full amount, and they include an annual out-of-pocket limit. After you reach that limit, the plan covers 100% of covered services for the rest of the year.
• Plan M sits between the simpler and the more comprehensive options, covering half of the Part A deductible along with other core benefits.

Why C and F are closed to newer enrollees

Plans C and F — and high-deductible F — remain in force for people who already had them, but they are closed to anyone who became eligible for Medicare on or after January 1, 2020. The reason is a federal rule prohibiting new Medigap policies from covering the Part B deductible. If you were eligible before that date and never enrolled, you may still be able to buy one; otherwise, Plan G is often described as the modern analogue, since it mirrors F except for the Part B deductible.

Medigap and prescription drugs

Medigap does not cover prescription drugs. If you want drug coverage with Original Medicare and a Medigap plan, you add a stand-alone Part D plan. A few program-level facts worth knowing as you plan:

• The Part D out-of-pocket cap is $2,100 in 2026 and rises to $2,400 in 2027.
• The maximum deductible a Part D plan can charge in 2027 is $700.
• The national Part D base beneficiary premium for 2027 is $41.33, which is used to calculate the late-enrollment penalty; actual plan premiums are set plan by plan.
• Annual Enrollment runs October 15 through December 7, 2026, with changes effective January 1, 2027.
• Social Security announced a 3.6 percent COLA for benefits payable beginning January 2027.

The 2027 Part B standard premium and deductible, and the 2027 IRMAA income brackets, have not yet been announced; CMS typically releases those figures in the fall.

Medigap vs. Medicare Advantage, briefly

Some people pair Original Medicare with Medigap and a Part D plan; others choose a Medicare Advantage plan that bundles Parts A, B and usually D into one policy, sometimes with extras but with network and prior-authorization rules. Neither path is better in the abstract — it depends on your doctors, your travel habits, your budget, your tolerance for paperwork and your health picture. It's worth thinking carefully about both.

A note for people with Medicaid or Extra Help

Since 2025, people with Medicaid or Extra Help have a monthly Special Enrollment Period to switch to Original Medicare with a stand-alone Part D plan, or to change stand-alone Part D plans. Full-benefit dual-eligible individuals can also join an integrated Dual Eligible Special Needs Plan (D-SNP) in any month.

Where to go next

For official plan comparisons, the Medigap rules in your situation, and the current letter chart, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), available 24 hours a day, seven days a week. Taking time to read the standardized benefit summary for each letter — and then comparing carriers that sell that letter — is often the most useful way to narrow things down.