Medicare Supplement

Medigap A Through N: How the Letter Plans Actually Work

JACKSON, Mich. — If you have ever tried to shop for a Medicare Supplement policy, you know the alphabet soup can be dizzying. Plan A, Plan G, Plan N — the letters look random, but they actually follow a strict federal script. In Jackson and across the country, every Medigap policy sold under the same letter must cover the same core benefits, no matter which insurance company sells it.

That standardization is meant to make comparison shopping easier. Once you understand what the letters mean, the choice comes down to price, service, and the carrier behind the card.

What Medigap is — and what it is not

Medicare Supplement Insurance, better known as Medigap, is a private policy that helps pay some of the out-of-pocket costs Original Medicare leaves behind. That means deductibles, coinsurance, and copayments under Part A (hospital) and Part B (doctor and outpatient) care.

Medigap is not Medicare Advantage. Advantage plans (Part C) replace the way you receive your Medicare benefits and usually bundle in extras. Medigap sits alongside Original Medicare and simply picks up part of your share of the bill. You cannot have both a Medigap policy and a Medicare Advantage plan at the same time.

Medigap also does not include prescription drug coverage. For that, you need a separate Part D plan.

Why the letters exist

Before the 1990s, Medigap policies were a mess of mismatched benefits. Congress stepped in and directed the federal government, working with state regulators, to standardize the plans. Today, most states — including Michigan — offer plans labeled A, B, C, D, F, G, K, L, M, and N. (Massachusetts, Minnesota, and Wisconsin have their own systems.)

Each letter is a benefit package defined by law. So a Plan G sold by one carrier in Jackson covers exactly the same Medicare gaps as a Plan G sold by another carrier down the road. The premium and customer service can differ. The core benefits cannot.

What the letters generally cover

Every standardized plan (A through N) covers a baseline that includes Part A hospital coinsurance and an extra 365 days of hospital coverage after Medicare benefits are used up. Most also cover Part B coinsurance, the first three pints of blood, and hospice coinsurance.

From there, the plans differ in how much of the remaining gaps they fill:

• Plans C and F are the most comprehensive but are only available to people who became eligible for Medicare before January 1, 2020.
• Plan G is often the most complete option for newer enrollees.
• Plans K and L have lower premiums but require you to pay a share of costs up to an annual limit.
• Plan N typically has lower premiums in exchange for small copays at doctor and emergency room visits.

For the full benefit grid, Medicare.gov publishes a side-by-side chart of every letter.

The enrollment window that matters most

The best time to buy a Medigap policy is during your Medigap Open Enrollment Period — a one-time, six-month window that begins the month you are 65 or older and enrolled in Part B. During this period, insurers must sell you any Medigap policy they offer at their best available rate, regardless of your health history.

Miss that window, and in most states carriers can use medical underwriting — meaning they can charge you more or turn you down based on your health. Jackson is in Jackson County, where the same federal Medigap rules apply as everywhere else in Michigan.

Medigap and Part D work together

Because Medigap does not cover prescriptions, most people who choose Original Medicare plus a Medigap policy also enroll in a stand-alone Part D drug plan. A few 2026 numbers to keep in mind:

• The Part D out-of-pocket cap is $2,100 for the year.
• The maximum Part D deductible is $615.
• The old coverage gap (the "donut hole") is gone; drug coverage now has three phases.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly installments if you choose.
• IRMAA surcharges for higher earners begin above $109,000 in income for a single filer.

Part D enrollment changes happen during the Annual Enrollment Period, October 15 through December 7.