Medicare Supplement

Medigap Plans A, G, and N: A Chicago Medicare Guide

CHICAGO — If you're new to Medicare, or helping a parent sort through the mail piling up on the kitchen table, you've probably run across something called Medigap. You may have also noticed the plans go by single letters — Plan A, Plan G, Plan N, and so on. It looks a little like alphabet soup, but there's a straightforward system behind it.

Here's a plain-language look at what Medicare Supplement Insurance actually does, why the letters matter, and how to think about it if you live in Chicago or anywhere in Cook County.

What Medigap is — and what it isn't

Medigap is private insurance that works alongside Original Medicare (Part A and Part B). It helps pay some of the out-of-pocket costs Original Medicare leaves behind — things like coinsurance, copayments, and hospital deductibles.

A few things Medigap is not:

• It is not the same as Medicare Advantage (Part C). You can't have both at the same time.
• It does not include prescription drug coverage. For that, you'd add a separate Part D plan.
• It does not typically cover dental, vision, hearing, or long-term care.

Think of Medigap as a co-pilot for Original Medicare. Medicare pays its share first, and your Medigap plan picks up some — or in some cases, most — of what's left.

Why the letters exist

Before the early 1990s, Medigap plans were a mess. Every insurance company sold something different, and shoppers had a hard time comparing. Congress stepped in and standardized the plans.

Today, in most states including Illinois, Medigap plans come in 10 standardized versions, each labeled with a letter: A, B, C, D, F, G, K, L, M, and N. (Massachusetts, Minnesota, and Wisconsin do things a little differently.)

Here's the key point: the benefits inside each lettered plan are set by federal law. A Plan G sold by one company in Chicago covers the same core benefits as a Plan G sold by another company down the street. What can differ is the price, the customer service, and things like household discounts.

What the letters actually cover

Each letter is a specific package of benefits. Some plans are fuller; others are lighter and less expensive. A few things to know:

• Plan F and Plan C are only available to people who became eligible for Medicare before January 1, 2020. If you turned 65 after that date, these two are off the table for you.
• Plan G and Plan N are the most common choices for people newly eligible today.
• Plans K and L have lower premiums but higher out-of-pocket limits — you share more of the cost until you hit a yearly cap.

You can see a side-by-side chart of what each letter covers at Medicare.gov.

When you can buy Medigap matters — a lot

This is the part many people wish they'd known earlier. The best time to buy a Medigap policy is during your Medigap Open Enrollment Period — a six-month window that begins 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. Once it closes, in most states — Illinois included — insurers can use medical underwriting. That means a health condition could raise your premium or, in some cases, keep you from switching plans later.

There are limited exceptions called "guaranteed issue rights," but they don't cover every situation. If you're approaching 65 in Chicago, mark that six-month window on the calendar.

How Medigap fits with Part D and the 2026 changes

Because Medigap doesn't include drug coverage, most people pair it with a stand-alone Part D prescription drug plan. A few 2026 figures worth knowing:

• The Part D out-of-pocket cap is $2,100 in 2026. Once you hit that, you pay $0 for covered drugs the rest of the year.
• The Part D maximum deductible is $615.
• The old "donut hole" coverage gap was eliminated in 2025 — Part D now has three phases instead of four.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly installments instead of paying at the pharmacy counter.
• IRMAA surcharges — extra amounts higher-income enrollees pay for Part B and Part D — start above $109,000 in income for a single filer in 2026.

The Annual Enrollment Period for Part D and Medicare Advantage runs October 15 through December 7. Medigap has its own rules and isn't tied to that window.

What Chicago residents should know about availability

Chicago is in Cook County, where Medicare plan options are handled at the county level, not the city level. Medigap is regulated by the Illinois Department of Insurance, and many carriers sell the standardized letter plans across the state.

Because the benefits inside each letter are identical by law, shopping is mostly about comparing price and the insurer itself — its stability, its customer service, and how it handles rate increases over time.