Medicare Supplement

Medigap in Bay City: the letter plans, decoded

BAY CITY, Mich. — If you're new to Medicare, or helping a parent sort through the mail piling up on the kitchen table, "Medigap" is one of those words that shows up everywhere without much explanation. Here in Bay City, where a lot of folks stay on Original Medicare and want predictable bills, understanding what Medigap actually does — and what those letter plans really mean — can take a lot of the guesswork out of the decision.

What Medigap is, in plain terms

Medicare Supplement Insurance, better known as Medigap, is a private policy that fills in some of the gaps in Original Medicare (Part A hospital and Part B medical). Original Medicare pays most of your covered costs, but not all of them. You still owe deductibles, coinsurance, and copays, and there's no yearly cap on what you might spend out of pocket.

A Medigap policy is designed to pick up some or all of those leftover costs, depending on which lettered plan you buy. You keep Original Medicare as your main coverage, and Medigap works quietly in the background to handle the pieces Medicare doesn't finish paying.

How the standardized letter plans work

In most states, including Michigan, Medigap plans are standardized by the federal government. That means Plan G from one insurance company covers the exact same core benefits as Plan G from another company. The price can be different, and customer service can be different, but the benefits inside a letter plan are the same.

Ten standardized plans are currently sold: A, B, C, D, F, G, K, L, M, and N. Each letter is a fixed benefit package. Some cover almost everything Original Medicare doesn't; others cover less in exchange for a lower premium. Two of them (Plans C and F) are only available to people who were eligible for Medicare before January 1, 2020. For anyone who became Medicare-eligible after that date, Plans G and N are the more comprehensive options still on the market.

You can compare the benefits side by side on the official Medicare.gov Medigap tool.

What Medigap does not cover

This part surprises a lot of readers. Medigap does not include:

• Prescription drugs. For that, you'd add a stand-alone Part D drug plan. (In 2026, Part D has a $2,100 annual out-of-pocket cap and a maximum deductible of $615.)
• Routine dental, vision, hearing aids, or long-term care.
• Anything if you're enrolled in a Medicare Advantage plan. Medigap only pairs with Original Medicare — you can't legally use both at once.

So the usual setup for a Bay City resident who chooses this route looks like: Original Medicare + a Medigap letter plan + a separate Part D plan.

Bay City's local picture

Bay City is in Bay County, and Medicare plan availability in this area is set at the county level. Bay County residents have access to a range of Medicare Advantage and Part D options through the Medicare Plan Finder, along with Medigap policies from multiple insurers licensed in Michigan. The Medigap side isn't listed as a "count of plans" the same way Advantage is — instead, you're shopping among carriers that each sell some or all of the standardized letters.

If you'd like unbiased help sorting through your options, Michigan's SHIP program — called MMAP (Medicare/Medicaid Assistance Program) — offers free counseling by phone and, in many communities, in person.

Timing matters more than most people realize

The single most important thing to know about buying Medigap is timing. Your Medigap Open Enrollment Period is a six-month window that begins the month you're 65 or older AND enrolled in Part B. During that window, insurers must sell you any Medigap plan they offer at their standard rate, regardless of your health history.

Outside that window, in most cases, insurers in Michigan can use medical underwriting — meaning they can ask about your health, and they can charge more or decline coverage based on the answers. This is different from the fall Annual Enrollment Period (Oct. 15 – Dec. 7), which applies to Medicare Advantage and Part D, not Medigap.