Medicare Supplement

How Medigap's lettered plan system works in Helena

HELENA, Mont. — If you've ever sat at your kitchen table staring at a Medicare mailer that lists "Plan A, Plan G, Plan N" and wondered whether those letters mean anything, you're not alone. Medicare Supplement insurance — often called Medigap — uses a lettered system that can look confusing at first glance but is actually designed to make shopping easier.

A Helena guide to Medicare Supplement plans

Here in Helena, and across Lewis and Clark County, Medigap works the same way it does everywhere else in the country (with a few state-specific rules we'll get to). Here's what the letters mean and how the coverage fits alongside the rest of Medicare.

What Medigap actually does

Medigap is private insurance that helps pay some of the out-of-pocket costs that Original Medicare (Part A and Part B) leaves behind — things like coinsurance, copayments, and deductibles. It only works with Original Medicare. If you're enrolled in a Medicare Advantage plan, you can't also use a Medigap policy.

A Medigap plan doesn't replace Medicare. It sits on top of it. You still pay your Part B premium, and then a separate premium to the private insurer for your Medigap coverage.

Medigap also doesn't include prescription drug coverage. For that, most people add a stand-alone Part D drug plan.

Why the plans are labeled with letters

Here's the part that trips people up. Medigap plans sold today are standardized by the federal government. That means Plan G from one company covers the exact same set of Medicare gaps as Plan G from any other company. The benefits are identical — only the price, the customer service, and the company name change.

According to Medicare.gov, in most states there are 10 standardized plan letters currently available: 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.)

Some letters cover a little. Some cover a lot. Plan A is the most basic. Plan G is one of the most comprehensive available to new enrollees. Plan K and Plan L have lower premiums but ask you to share more of the cost up front.

The point of the letter system is simple: two people can compare the same "Plan G" from two different insurers and know they're comparing apples to apples.

When you can buy a Medigap policy in Montana

Timing matters — a lot. 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 that window, insurance companies can't turn you down or charge you more because of your health.

Outside that window, in most states, insurers can use medical underwriting. That means they can look at your health history and either deny coverage or charge a higher premium.

Montana has some additional protections in certain situations — for example, guaranteed-issue rights when you lose other coverage — so it's worth checking with the Montana State Health Insurance Assistance Program (SHIP), which offers free counseling.

How Medigap fits with the rest of Medicare in 2026

Medigap doesn't change how Part D drug plans work, but it's helpful to know what's happening on the drug side in 2026:

• Part D has a new $2,100 out-of-pocket cap on covered prescriptions.
• The Part D maximum deductible is $615.
• The old "donut hole" is gone; Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the year.
• IRMAA income-based surcharges start above $109,000 for single filers in 2026.

If you're weighing Original Medicare + Medigap + Part D versus Medicare Advantage, these Part D changes are part of the picture — but they don't change how Medigap itself works.

A quick word on picking a letter

Because benefits are standardized, three things really drive the decision:

1. How much coverage do you want up front vs. how much are you willing to pay in premiums? 2. How does the insurer price the plan? Companies use different pricing methods — community-rated, issue-age-rated, or attained-age-rated — and premiums can rise differently over time. 3. Do you travel? Some letters include foreign travel emergency coverage.

This is where a SHIP counselor can be genuinely useful. They don't sell anything.