Medicare Supplement

Understanding Medigap Plan Letters: A Clear Guide

HILTON HEAD ISLAND, S.C. — If you've been reading up on Medicare, you've probably run into a confusing alphabet: Plan A, Plan G, Plan N, Plan K, and more. These are Medigap plans — also called Medicare Supplement Insurance — and the letters are actually good news for consumers. They mean the benefits are standardized, so a Plan G from one company covers the same core things as a Plan G from another. Here's what that really means for you.

What Medigap Is (and Isn't)

Medigap is private insurance that works alongside Original Medicare (Part A and Part B). It helps pay some of the out-of-pocket costs Original Medicare leaves behind — things like coinsurance, copayments, and deductibles.

A few important points:

• Medigap is not Medicare Advantage. You can't have both at the same time.
• Medigap generally doesn't include prescription drug coverage. For drugs, most people pair Medigap with a stand-alone Part D plan.
• You pay a monthly premium to the insurance company on top of your Part B premium.

Because Medigap works with Original Medicare, you can typically see any doctor or hospital in the country that accepts Medicare — a feature many Hilton Head Island retirees appreciate, especially if they travel or split time between states.

Why the Letters Exist

Before the letters were standardized, Medigap plans were a mess. Two policies with similar names could cover very different things, and it was hard to compare shop.

To fix that, federal law standardized Medigap plans. Today, in most states, plans are sold under letter names — A, B, C, D, F, G, K, L, M, and N. (Massachusetts, Minnesota, and Wisconsin use their own systems.)

Here's the key idea: within a letter, the benefits are identical no matter which company sells it. A Plan G is a Plan G. What can differ is the price, the customer service, and how the company handles rate increases over time.

What Each Letter Generally Covers

Every lettered plan covers a set of basic benefits, including Part A hospital coinsurance and an extra 365 days of hospital coverage after Medicare benefits are used up. From there, the letters cover different combinations of extras, such as:

• Part B coinsurance or copayments
• The first three pints of blood
• Hospice care coinsurance
• Skilled nursing facility coinsurance
• Part A and Part B deductibles
• Foreign travel emergency care (up to plan limits)

Plans K and L are cost-sharing plans, meaning you pay a percentage until you hit an out-of-pocket limit. Plan N has small copays for some office and ER visits. For a side-by-side chart, medicare.gov keeps the official comparison up to date.

An Important Note About Plans C and F

If you became eligible for Medicare on or after January 1, 2020, you cannot buy Plans C or F. That's because those plans covered the Part B deductible, and federal law now prevents new Medigap plans from doing so.

People who were already eligible before that date can generally still keep or buy those plans. Plan G has become a popular alternative because it covers most of the same things — just not the Part B deductible.

When You Can Buy Medigap Matters

The best time to buy a Medigap policy is during your Medigap Open Enrollment Period — the six months that start the month you're 65 or older and enrolled in Part B. During this window, companies must sell you any Medigap plan they offer at the best available rate, regardless of your health history.

Outside that window, in most states, insurers can use medical underwriting. That means they can charge you more, or turn you down, based on your health. A few states have stronger consumer protections, so it's worth checking your state's rules.

Hilton Head Island is in Beaufort County, and South Carolina follows the federal rules — so timing your enrollment carefully really matters.

How Medigap Fits With Other 2026 Medicare Changes

Medigap is separate from Part D, but the two often go together. A few 2026 facts worth knowing as you plan:

• Part D now has a $2,100 annual out-of-pocket cap on covered drugs.
• The Part D maximum deductible is $615.
• The old "donut hole" coverage gap is gone; Part D now has three simpler phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the year in monthly installments.
• IRMAA income surcharges start above $109,000 for single filers in 2026.
• The Annual Enrollment Period runs October 15 – December 7, and Medicare Advantage Open Enrollment runs January 1 – March 31.

None of those directly change how Medigap works, but they affect the overall picture of what you'll pay each year.