Medicare Supplement

How Medigap's Lettered Plans Work: A Plain-English Guide

SAN ANTONIO — If you've spent any time looking at Medicare Supplement Insurance, you've probably run into a wall of letters: Plan A, Plan G, Plan N, Plan K, and so on. It can feel like alphabet soup. The good news? Once you know how the letters work, Medigap becomes one of the easier corners of Medicare to understand.

Medigap in San Antonio: What the Letters Actually Mean

Here's a plain-English guide to what Medigap does, why the letters exist, and what San Antonio residents should know before making a decision.

What Medigap Does (and Doesn't Do)

Medigap is private insurance you can buy to help pay some of the out-of-pocket costs that Original Medicare (Part A and Part B) leaves behind — things like coinsurance, copayments, and certain deductibles.

A few key points to keep in mind:

• Medigap only works with Original Medicare. It does not work with Medicare Advantage plans.
• Medigap does not include prescription drug coverage. For that, you'd add a separate Part D plan.
• You pay a monthly premium to the insurance company for a Medigap policy, on top of your Part B premium.
• Medigap generally does not cover dental, vision, hearing, or long-term care.

Think of it this way: Original Medicare pays its share of a covered service, and your Medigap plan helps pick up some or all of what's left.

Why the Letters Exist

Here's where things get simpler than they look. Medigap plans are standardized by the federal government. That means a Plan G sold by one insurance company covers the exact same set of benefits as a Plan G sold by another company. The benefits inside each letter are set by law.

What can differ between companies:

• The monthly premium
• Customer service
• Whether household or other discounts are offered
• How the company handles rate increases over time

So when you compare Medigap plans of the same letter, you're mostly comparing price and the company behind the policy — not the benefits themselves.

Currently, Medigap plans are labeled A, B, C, D, F, G, K, L, M, and N. (Massachusetts, Minnesota, and Wisconsin standardize their plans a little differently, but Texas follows the standard federal lettering.)

An Important Note About Plans C and F

If you became eligible for Medicare on or after January 1, 2020, you generally cannot buy Plan C or Plan F. That's because those plans cover the Part B deductible, and a federal law closed them to newly eligible beneficiaries.

If you were eligible for Medicare before that date, you may still be able to buy them. This is one of the most common points of confusion, so it's worth knowing where you stand.

When You Can Buy a Medigap Plan Without Health Questions

This is the piece many people wish they'd known sooner. You have a one-time Medigap Open Enrollment Period that starts the month you're 65 or older AND enrolled in Part B. It lasts six months.

During that window:

• Insurance companies must sell you any Medigap plan they offer.
• They cannot charge you more because of health conditions.
• They cannot turn you down.

Once that six-month window closes, in most states — Texas included — insurers can use medical underwriting. That means they can ask health questions and potentially deny coverage or charge more. There are a few limited "guaranteed issue" situations later on, but they are narrower than most people expect.

Missing this window is one of the most common and costly Medigap mistakes.

Medigap vs. Medicare Advantage: They Are Not the Same

San Antonio is in Bexar County, where Medicare beneficiaries have a wide range of Medicare Advantage plans available. Advantage plans and Medigap policies work very differently, and you can't have both at the same time.

• Medicare Advantage replaces the way you get your Original Medicare benefits and often bundles in extras.
• Medigap works alongside Original Medicare to help pay cost-sharing.

Choosing between the two paths is a personal decision based on your doctors, your health, your budget, and how you like to handle care. Neither one is right for everyone.

A Few 2026 Numbers Worth Knowing

Even if you're focused on Medigap, some Medicare figures affect the bigger picture:

• The Part D out-of-pocket cap is $2,100 in 2026.
• The Part D maximum deductible is $615.
• The old coverage gap ("donut hole") was eliminated in 2025.
• IRMAA surcharges begin above $109,000 in income for a single filer in 2026.
• Annual Enrollment Period runs October 15 – December 7.
• Medicare Advantage Open Enrollment runs January 1 – March 31.

Note that Medigap enrollment is not tied to these fall/winter windows. Medigap has its own rules, centered on that six-month open enrollment period around your Part B start date.