Medicare Supplement

Medigap plan letters explained for Lewisville households

LEWISVILLE, Texas — If you're new to Medicare, or helping a parent sort through the mail piling up on the kitchen table, you've probably run into the word "Medigap." You may have also seen a confusing alphabet — Plan A, Plan G, Plan N, Plan K — and wondered what any of it means.

Medicare Supplement insurance, explained: what Medigap does and doesn't cover

Here's the plain-English version: Medigap, also called Medicare Supplement insurance, is a private policy that helps pay some of the costs Original Medicare leaves behind. It works alongside Parts A and B, not instead of them. And thanks to federal rules, the letter plans are standardized — so a Plan G sold by one company covers the same core benefits as a Plan G sold by another.

Let's walk through how it works.

What Medigap actually does

Original Medicare (Part A for hospital care and Part B for doctor visits) pays a large share of your covered medical costs — but not all of them. You're still on the hook for things like the Part A hospital deductible, the 20% coinsurance under Part B, and other out-of-pocket amounts that can add up quickly if you have a serious health event.

A Medigap policy is designed to fill some of those gaps. Depending on which lettered plan you pick, it may help pay:

• Part A hospital coinsurance and extra hospital days
• Part B coinsurance or copayments
• The first three pints of blood
• Hospice care coinsurance
• Skilled nursing facility coinsurance
• The Part A deductible
• Emergency care during foreign travel (on some plans)

Medigap does not cover prescription drugs (you'd need a separate Part D plan for that), and it doesn't pay for dental, vision, hearing aids, long-term care, or private-duty nursing. It also can't be used with a Medicare Advantage plan — Medigap only works with Original Medicare.

How the standardized letters work

Under federal law, Medigap plans in most states are sold under standardized letter names: A, B, C, D, F, G, K, L, M, and N. (Massachusetts, Minnesota, and Wisconsin have their own systems.)

Standardization is the important part. If two companies both sell Plan G, the benefits inside those two policies are identical. What can differ is the price — and, sometimes, extras a carrier adds on, like a fitness perk.

A few things worth knowing:

• 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, they're off the table.
• Plan G is often the most comprehensive option available to newly eligible enrollees. It covers everything Plan F covered, except the Part B deductible.
• Plan N typically has lower premiums but asks you to pay small copays for some office and ER visits.
• Plans K and L have lower premiums with cost-sharing and an annual out-of-pocket limit.

The best time to buy — and why timing matters

The strongest consumer protection in Medigap is your six-month Medigap Open Enrollment Period. It starts 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 history.

Miss that window, and in most states insurers can use medical underwriting — meaning they can review your health and either raise your rate or decline your application. There are a few limited "guaranteed issue" situations (for example, losing certain coverage through no fault of your own), but the six-month window is by far the safest time to shop.

Lewisville is in Denton County, and Texas follows the federal rules on the Medigap Open Enrollment Period. If you're weighing Medigap against Medicare Advantage, this timing question is a big deal — switching from Advantage to Medigap later isn't always guaranteed.

Medigap vs. Medicare Advantage: two different roads

This is where a lot of readers get tripped up. Medigap and Medicare Advantage (Part C) are not the same, and you can't have both.

• Medigap works with Original Medicare. You can generally see any doctor or hospital in the country that accepts Medicare. You pay a monthly Medigap premium in addition to your Part B premium, and usually a separate Part D drug plan.
• Medicare Advantage replaces Original Medicare with a private plan that bundles Parts A, B, and often D together, usually with a network of doctors.

Neither is "better" — they're different tools. Your health, your budget, whether you travel, and which doctors you want to keep all matter.

What Medigap does not touch: drugs

Medigap won't help with prescription costs. For that, you'd enroll in a stand-alone Part D drug plan.

Some 2026 Part D figures worth writing down:

• The annual out-of-pocket cap for covered drugs is $2,100.
• The maximum Part D deductible is $615.
• The old coverage gap ("donut hole") is gone as of 2025 — Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly payments instead of paying big amounts at the pharmacy counter.

If your income is above $109,000 as a single filer in 2026, you may pay an IRMAA surcharge on top of your Part B and Part D premiums.