Medicare Supplement

How Medigap Letters Work for Milwaukee Medicare Enrollees

MILWAUKEE — If you've ever tried to read up on Medicare Supplement Insurance, you've probably run into a wall of letters: Plan A, Plan B, Plan D, Plan G, Plan K, Plan N. It looks confusing, but there's actually a helpful reason behind those letters. They're standardized, which means once you understand what each letter covers, comparing options gets a lot simpler.

Making sense of the Medigap alphabet

Here in Milwaukee — and across Milwaukee County — the rules for these plans work the same way they do anywhere else in Wisconsin. (Wisconsin is one of three states with its own version of standardization, which we'll get to in a minute.) Let's walk through what Medigap does, what it doesn't do, and the mistakes people most often make when picking one.

What Medigap actually is

Medigap is private insurance that works alongside Original Medicare (Part A and Part B). It doesn't replace Medicare. Instead, it helps pay some of the out-of-pocket costs Original Medicare leaves behind — things like coinsurance, copayments, and in some cases the Part A hospital deductible.

A few important points about Medigap, straight from Medicare.gov:

• You must be enrolled in both Part A and Part B to buy a Medigap policy.
• Medigap does not work with Medicare Advantage. You can only have one or the other.
• Medigap policies generally don't include prescription drug coverage. For that, you'd add a separate Part D plan.
• Each Medigap policy covers one person. Spouses need their own policies.

Why the letters exist

Before standardization, Medigap plans were a mess to compare. Congress fixed that. Today, in most states, Medigap plans come in ten standardized letters: A, B, C, D, F, G, K, L, M, and N. Every Plan G, for example, covers the exact same set of benefits no matter which insurance company sells it. What can differ is the premium — the monthly price — and the customer service you get from the carrier.

That's the key insight: because benefits are identical letter-for-letter, the shopping process is really about price, the company's reputation, and how they handle rate increases over time.

A few notes worth remembering:

• Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. If you turned 65 after that date, these two aren't on the menu for you.
• Plan G and Plan N are the two most talked-about options for newer enrollees, but you should compare all the letters you qualify for.
• Plans K and L have lower premiums but cap how much they pay in cost-sharing, leaving more for you to pay up front.

Wisconsin does it a little differently

Here's where Milwaukee readers need to pay closer attention. Wisconsin, along with Minnesota and Massachusetts, doesn't use the standard letter system. Instead, Wisconsin has its own standardized Medigap structure built around a basic plan with optional riders you can add — for example, a Part A deductible rider or a copayment rider.

The idea is the same — every insurance company selling the "basic Wisconsin plan" must offer the same core benefits — but the packaging looks different from what you'll read about on national websites. If you're comparing plans in Milwaukee County, ask insurers specifically about the Wisconsin standardized basic plan and which riders are included in the quote. That way you're comparing apples to apples.

The enrollment window that matters most

The single most costly mistake people make with Medigap has nothing to do with picking the wrong letter. It's missing the Medigap Open Enrollment Period.

This is a six-month window that starts the month you're 65 or older and enrolled in Part B. During this window, insurance companies must sell you any Medigap policy they offer at their best available rate, regardless of your health history. They can't turn you down for pre-existing conditions, and they can't charge you more because of them.

After that window closes, in most cases, insurers can use medical underwriting. That means they can ask about your health, charge you more, or decline coverage altogether. Wisconsin has some additional guaranteed-issue protections in certain situations, but the safest bet is to make your Medigap decision during that first six-month window.

Common mistakes to avoid

• Assuming Medigap includes drug coverage. It doesn't. You'll want to look at Part D separately. For 2026, Part D has a $2,100 annual out-of-pocket cap and a maximum deductible of $615, per Medicare.gov.
• Trying to have Medigap and Medicare Advantage at the same time. It's not allowed. Switching between the two is possible, but timing and underwriting rules can get tricky.
• Shopping only on premium. The cheapest premium today may rise sharply later. Ask each company about their history of rate increases.
• Waiting past your open enrollment window. Health can change fast. Locking in coverage while you have guaranteed-issue rights is the safer path.