Medicare Supplement

Understanding the Medigap Plan Letters, From A to N

HOUSTON, Texas — If you've been shopping for a Medicare Supplement policy, you've probably run into a wall of letters: Plan A, Plan G, Plan N, and several in between. It's confusing at first glance, but there's a reason for the alphabet soup — and once you understand it, comparing coverage gets much easier.

Here's what Medicare Supplement Insurance (better known as Medigap) actually does, and how those standardized letters are meant to help you.

What Medigap Is — and What It Isn't

Medigap is private insurance you can buy to work alongside Original Medicare (Part A and Part B). It helps pay some of the out-of-pocket costs Original Medicare leaves behind, such as coinsurance, copayments, and deductibles.

A few important points to keep straight:

• Medigap only works with Original Medicare. It does not work with Medicare Advantage.
• Medigap policies generally do not include prescription drug coverage. For that, you'd add a separate Part D plan.
• You pay a monthly premium for the Medigap policy, on top of your Part B premium.

Medigap is sold by private insurance companies, but the benefits inside each lettered plan are set by federal and state rules — not by the insurer.

Why the Plans Are Labeled With Letters

In most states, including Texas, Medigap plans are standardized. That means every "Plan G" sold by every insurance company covers the exact same set of benefits. A Plan G from one carrier is the same Plan G from any other carrier, benefit-for-benefit.

What can differ between companies:

• The monthly premium
• Customer service and claims handling
• How they price policies as you age

So if two insurers both sell Plan G, they're selling the same coverage — but one may charge more than the other. That's what makes the letters so useful: they let you compare apples to apples.

The Letters Currently Sold

Medigap plans available today are labeled A, B, C, D, F, G, K, L, M, and N. (Plans E, H, I, and J are no longer sold to new enrollees, though older policies may still exist.)

Each letter offers a different mix of benefits. Some cover nearly all Medicare cost-sharing; others cover less and cost less. A few things to know:

• Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. If you're newly eligible, you can't buy them.
• Plans K and L have annual out-of-pocket limits after which the plan pays 100% of covered costs.
• Plan N typically requires small copays for some office and emergency room visits.

For a full grid comparing what each letter covers, medicare.gov keeps an up-to-date chart.

Houston Shoppers: A Note on Where You Live

Houston sits mostly in Harris County, with parts stretching into Fort Bend, Montgomery, and Brazoria counties. Medigap availability is set at the state and carrier level rather than by county, so which companies sell which lettered plans in your ZIP code can vary. You can search available Medigap policies in your area using the "Find a Medigap policy" tool on medicare.gov.

The Enrollment Window That Matters Most

The single most important thing to know about Medigap is the Medigap Open Enrollment Period. This is a one-time, six-month window that starts the month you're 65 and enrolled in Part B.

During that window:

• You can buy any Medigap policy sold in your state.
• Insurers cannot deny you coverage or charge you more because of health problems.

Outside that window, in most states, insurance companies can use medical underwriting — meaning they can ask health questions and turn you down or charge more. Texas follows this general rule. Missing your six-month window can quietly become one of the more costly Medicare mistakes.

This is a separate deadline from the fall Annual Enrollment Period (October 15 – December 7), which applies to Medicare Advantage and Part D, not Medigap.

How Medigap Fits With Part D and the 2026 Changes

Because Medigap doesn't include drug coverage, many people with Medigap also enroll in a stand-alone Part D plan. A few 2026 program-level figures worth knowing:

• Part D has a new $2,100 annual out-of-pocket cap on covered drugs.
• 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 if you choose.
• IRMAA surcharges on Part B and Part D premiums start above $109,000 in income for single filers in 2026.

None of these change Medigap directly, but they affect the total picture if you pair Medigap with a Part D plan.