Medicare Supplement

Medigap, Explained: What Medicare Supplement Plans Actually Cover

ROCHESTER, Minn. — If Original Medicare feels like it leaves some gaps in your budget, you're not imagining it. Medicare Part A and Part B pay for a lot, but they don't pay for everything. That's where Medicare Supplement insurance — usually called Medigap — comes in.

Medigap is private insurance you can buy to help cover some of the out-of-pocket costs Original Medicare leaves behind, like deductibles, copayments, and coinsurance. What makes it different from most insurance is that the benefits are standardized by the federal government. Once you understand the letter system, comparing plans gets a lot simpler.

What Medigap is — and what it isn't

Medigap works alongside Original Medicare (Parts A and B). After Medicare pays its share of a covered service, your Medigap plan pays some or all of what's left, depending on the letter you chose.

A few things Medigap does not do:

• It is not Medicare Advantage (Part C). You can't have both at the same time.
• It generally does not include prescription drug coverage. For that, most people add a stand-alone Part D plan.
• It does not usually cover routine dental, vision, hearing aids, or long-term care.

If you have a Medigap policy, you still keep your red, white, and blue Medicare card and use it at the doctor. The Medigap plan just handles the leftover bills.

How the standardized letters work

In most states, Medigap plans come in 10 versions labeled by letter: A, B, C, D, F, G, K, L, M, and N. Every plan of a given letter must cover the same core benefits, no matter which insurance company sells it. A Plan G from one carrier covers the same things as a Plan G from another — the price and customer service may differ, but the benefits do not.

A couple of important notes from Medicare.gov:

• Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. If you turned 65 in 2020 or later, those two aren't on the menu.
• Plans K and L have yearly out-of-pocket limits, then pay 100% of covered services for the rest of the year.
• Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans differently, so if you live in Rochester, the plan options you see will follow Minnesota's rules rather than the letter system used in most other states.

The best time to buy: your Medigap Open Enrollment Period

Timing matters more with Medigap than almost any other Medicare decision. 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 this window, you have a "guaranteed issue" right: insurers must sell you any Medigap policy they offer at their best available rate, and they can't turn you down or charge more because of past or current health problems.

Miss that window, and in most states insurers can use medical underwriting — meaning they can ask health questions, charge more, or decline coverage altogether. There are a few limited situations that also trigger guaranteed issue rights later (for example, if certain other coverage ends), but the six-month window at 65 is the safest bet.

Medigap and Part D go together

Because most Medigap plans don't include drug coverage, people who choose Medigap usually also enroll in a stand-alone Medicare Part D drug plan. A few 2026 numbers worth knowing:

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

What this looks like in Rochester

Rochester is in Olmsted County, and Medicare plan availability is set at the county level. Because Minnesota uses its own Medigap structure, Olmsted County residents will see Minnesota's standardized Basic and Extended Basic plans, plus optional riders, rather than the A-through-N letters common in most of the country. The core idea is the same: benefits are standardized, so you can compare across carriers on price and service.

For people also weighing Medicare Advantage instead of Original Medicare plus Medigap, remember the calendar:

• Annual Enrollment Period: October 15 – December 7
• Medicare Advantage Open Enrollment Period: January 1 – March 31