Medicare Supplement

Medigap Plan Letters Explained: A Plain-English Guide

LINCOLN PARK, Mich. — If you've started shopping for Medicare Supplement coverage, you've probably run into a puzzle: the plans are labeled with letters like A, G, and N. What do those letters mean, and why do they matter?

Here's a plain-English walk-through of how Medigap works and what the standardized letters are really telling you.

What Medigap actually does

Medicare Supplement Insurance — usually called Medigap — is private insurance that works alongside Original Medicare (Part A and Part B). After Medicare pays its share of a covered service, Medigap can pick up some or all of the costs Medicare leaves behind, like coinsurance, copayments, and deductibles.

A few important ground rules from Medicare.gov:

• You must be enrolled in Part A and Part B to buy a Medigap policy.
• Medigap only works with Original Medicare. It does not pair with a Medicare Advantage plan.
• Medigap does not include prescription drug coverage. For that, you'd add a separate Part D plan.
• You pay a monthly premium to the Medigap insurer, in addition to your Part B premium.

Why the letters exist

In most states, Medigap policies are standardized by the federal government. That means a Plan G sold by one company covers the exact same set of benefits as a Plan G sold by another company. The letter tells you what the plan covers — nothing more, nothing less.

Price and customer service can vary between companies, but the benefits inside each lettered plan are set by law. (Massachusetts, Minnesota, and Wisconsin standardize their plans a little differently.)

The letters you'll see

Today, Medigap plans are sold using these letters: A, B, C, D, F, G, K, L, M, and N. Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. Everyone else chooses from the remaining letters.

Each letter is a different mix of benefits. Some cover almost everything Original Medicare leaves behind. Others cover less and typically come with a lower premium. A few, like K and L, use an out-of-pocket limit and cost-sharing percentages instead of covering costs in full.

You can compare exactly what each letter covers side-by-side on the official chart at Medicare.gov.

Your best window to enroll

Timing matters more with Medigap than many people realize. Your Medigap Open Enrollment Period is a one-time, six-month window that starts the month you're 65 or older and enrolled in Part B. During this window:

• Insurers must sell you any Medigap policy they offer.
• They can't charge you more because of health problems.
• They can't turn you down.

Outside that window, in most states, insurers can use medical underwriting — meaning your health history can affect whether you're accepted or what you pay. That's why this window is worth marking on the calendar.

How this fits with Lincoln Park

Lincoln Park is in Wayne County, where Medicare beneficiaries have the same access to standardized Medigap plans as anyone else in Michigan. Medigap availability and pricing are regulated at the state level, so which insurers sell which letters — and at what price — is a Michigan question, not a city-by-city one.

If you're weighing Medigap against Medicare Advantage, remember that Advantage plans are a separate path with their own network and cost rules, and you can't use both at the same time.

A few 2026 numbers worth knowing

Medigap doesn't cover drugs, but if you also enroll in Part D, keep these 2026 program-level figures in mind:

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