Medicare Supplement

Medigap in Columbia: how the plan letters work

In Columbia, turning 65 often comes with a stack of mail about "Plan G," "Plan N," and other letters that look more like a hearing test than health coverage. Those letters are actually a helpful shortcut — one Medicare set up on purpose so you can compare Medicare Supplement (Medigap) policies without getting lost in fine print.

Here's what the letters mean, what Medigap does, and how it fits with the rest of your Medicare coverage in 2026.

What Medigap actually does

Original Medicare (Part A and Part B) pays a big share of your hospital and doctor costs, but not all of it. You're still responsible for things like the Part A hospital deductible, the 20% coinsurance under Part B, and certain other charges.

Medigap — short for Medicare Supplement Insurance — is a private policy that helps cover those leftover costs. You keep Original Medicare as your main coverage, and Medigap pays secondary.

Medigap does not cover prescription drugs. For that, most people add a separate Part D drug plan.

Why the plans are labeled by letter

Before standardization, comparing supplement policies was nearly impossible. Today, in most states, insurance companies can only sell Medigap policies that match a set of standardized benefit packages. Each package is named with a letter.

That means:

• A Plan G sold by one company covers the same core benefits as a Plan G sold by another company.
• Companies can charge different premiums for the same lettered plan.
• Customer service, billing, and extras (like discounts on gym memberships) can vary.

Massachusetts, Minnesota, and Wisconsin standardize their plans differently, but Missouri follows the common letter system.

The current lineup: A, B, D, G, K, L, M, and N (plus C and F for some)

As of 2026, the standardized Medigap plans available to most new enrollees are A, B, D, G, K, L, M, and N. Each letter offers a different mix of benefits — for example, some cover the Part A hospital deductible in full, while others cover a percentage.

Plans C and F are still around, but they're only available to people who were eligible for Medicare before January 1, 2020. That's because those plans cover the Part B deductible, and newer law doesn't allow first-dollar Part B coverage for people who became eligible after that date.

High-deductible versions of Plan G and Plan F exist too. You pay a lower premium in exchange for meeting a higher deductible before the plan starts paying.

To see side-by-side charts of what each letter covers, Medicare's official comparison tool at medicare.gov is the clearest place to start.

When you can buy Medigap — and why timing matters

The friendliest time to buy a Medigap policy is your Medigap Open Enrollment Period: a one-time, 6-month window that begins the first month you're both 65 or older and enrolled in Medicare Part B.

During this window:

• Companies must sell you any Medigap plan they offer.
• They can't charge you more because of health problems.
• They can't turn you down for pre-existing conditions (though a short waiting period may apply in some cases).

Outside that window, insurers in most states can use medical underwriting, which may affect price or eligibility. There are a few "guaranteed issue" situations — like losing other coverage — where protections still apply.

Medigap vs. Medicare Advantage

This part trips up a lot of readers, so it's worth spelling out:

• Medigap works with Original Medicare. You can add a stand-alone Part D drug plan.
• Medicare Advantage (Part C) replaces the way Original Medicare pays your claims. You cannot pair a Medigap policy with a Medicare Advantage plan.

Columbia is in Boone County, where residents can choose from a range of Medicare Advantage and Part D options each year during the Annual Enrollment Period (October 15 – December 7). If you're weighing Medigap vs. Advantage, that decision is separate from picking a lettered plan — it's really a choice about which side of Medicare you want to build on.

A quick word on drug costs in 2026

Medigap doesn't cover prescriptions, but since it often shares a mailbox with Part D questions, here are the 2026 numbers worth knowing:

• The Part D out-of-pocket cap is $2,100 for 2026.
• The maximum Part D deductible is $615.
• The old coverage gap ("donut hole") has been gone since 2025 — Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly payments instead of paying at the pharmacy counter.
• IRMAA surcharges on Part B and Part D premiums begin above $109,000 in income for a single filer in 2026.