Medicare Supplement

Medigap Letters Explained: What Each Plan Really Covers

EAGAN, Minn. — If you have Original Medicare (Part A and Part B), you know it covers a lot — but not everything. There are deductibles, coinsurance, and copays that can add up quickly, especially during a hospital stay. That's where Medicare Supplement Insurance, better known as Medigap, comes in.

The Basics of Medicare Supplement Insurance

Medigap is private insurance you can buy to help pay the out-of-pocket costs that Original Medicare leaves behind. It works alongside Medicare, not in place of it. Medicare pays its share first, and then your Medigap plan picks up some or all of what's left, depending on which plan letter you choose.

Here in Eagan, which sits in Dakota County, Medigap plans are sold by private insurance companies but are regulated at both the federal and state level. That regulation is what makes the "letter" system work.

What the Standardized Letters Mean

In most states, Medigap plans are standardized. That means a Plan G sold by one company covers the same core benefits as a Plan G sold by another company. The name of the insurer on the card may change, but the benefits behind that letter do not.

Today, the plans available to new enrollees are labeled with letters: A, B, D, G, K, L, M, and N. (Plans C and F are still held by people who had them before, but they are no longer sold to people who became eligible for Medicare on or after January 1, 2020.) Each letter offers a different mix of coverage — some pay for the Part A hospital deductible, some cover skilled nursing coinsurance, and some include limited foreign travel emergency care.

The takeaway: once you know the letter, you know what the plan covers. What can differ between companies is the price and the customer service, not the benefits.

Why the Letters Matter When You're Comparing

Because the benefits are locked in by letter, comparing Medigap plans is really a two-step process:

1. Pick the letter that matches the level of coverage you want. 2. Compare the premiums that different insurance companies charge for that same letter.

This is one of the areas where people make avoidable mistakes. It's easy to assume a higher premium means better coverage — but if two Plan G policies are standardized, the benefits are identical. You are paying for the company's pricing, stability, and service, not extra benefits.

The Enrollment Window You Don't Want to Miss

Here's the part that trips people up most: Medigap has its own enrollment rules, and they are different from the ones you may have heard about for Medicare Advantage or Part D.

Your best chance to buy a Medigap policy is during your Medigap Open Enrollment Period — the six months that begin the month you're 65 or older AND enrolled in Part B. During that window, you have "guaranteed issue" rights. That means an insurer cannot turn you down or charge you more because of your health history.

Miss that window, and in most states insurers can use medical underwriting. They may ask about your health, charge more, or deny coverage altogether. There are a few limited situations that give you guaranteed issue rights later, but they are narrow. This is why signing up on time matters so much.

Note: the Annual Enrollment Period (October 15 – December 7) and the Medicare Advantage Open Enrollment Period (January 1 – March 31) apply to other parts of Medicare — not to buying a Medigap plan.

How Medigap Fits With the Rest of Medicare

A few things to keep in mind as you think about how the pieces fit together:

• Medigap does not cover prescription drugs. For drug coverage, you'd add a separate Part D plan. In 2026, Part D has a $2,100 out-of-pocket cap and a maximum deductible of $615. The old coverage gap ("donut hole") was eliminated in 2025.
• You can't have Medigap and Medicare Advantage at the same time. Medigap only works with Original Medicare.
• Higher-income beneficiaries pay IRMAA surcharges on Part B and Part D. In 2026, those start above $109,000 in income for a single filer.

Dakota County residents have access to the same standardized Medigap letters available across Minnesota — though Minnesota is one of a small number of states that uses a slightly different standardization system, so it's worth asking specifically about how the letters translate here.

A Short FAQ

Q: If Plan G is the same everywhere, why do prices vary so much? A: Insurance companies set their own premiums. They also use different pricing methods — some rate by age at issue, some by your current age, and some charge everyone in a group the same. Over time, those methods can lead to very different costs.

Q: Can I switch from one Medigap plan to another later? A: You can apply anytime, but outside of your initial six-month window (or a special guaranteed issue situation), the insurer can use medical underwriting. Approval isn't guaranteed.

Q: Does Medigap cover dental, vision, or hearing? A: Generally, no. Medigap fills gaps in Original Medicare, and Original Medicare doesn't routinely cover those services.

Q: What if I already have Medicare Advantage — can I add Medigap? A: No. To use a Medigap policy, you'd need to return to Original Medicare first. There are specific times when that switch is allowed, so it's worth talking through the timing before making a change.

Where to Get Trustworthy Help

Medigap decisions are personal, and the right choice depends on your health, budget, and how you like to get care. Before you sign anything, use official resources:

• Medicare.gov — the official site, with a plan finder and side-by-side comparisons.
• 1-800-MEDICARE (1-800-633-4227) — available 24/7.
• Minnesota's State Health Insurance Assistance Program (SHIP), called the Senior LinkAge Line® (1-800-333-2433) — free, unbiased counseling for Minnesota residents, including folks here in Eagan and across Dakota County.

Take the time to understand the letter before you compare the prices. Once you know what Plan G, Plan N, or any other letter actually covers, the rest of the decision gets a lot simpler.