Medicare Supplement

Dallas guide to Medicare Supplement standardized letters

DALLAS — If you have Original Medicare and keep hearing about "Plan G" or "Plan N," you're bumping into one of the more confusing corners of Medicare: the Medigap letter system. The good news is that once you understand how the letters work, comparing Medicare Supplement policies gets a lot easier.

Medigap is private insurance you can buy to help pay some of the out-of-pocket costs Original Medicare leaves behind — things like coinsurance, copays, and deductibles. In most states, including Texas, the federal government has standardized these policies into lettered plans, so a Plan G from one company covers the same core benefits as a Plan G from another.

What Medigap actually does

Original Medicare (Part A and Part B) pays most of your hospital and doctor bills, but not all of them. You still owe deductibles, and Part B generally pays 80% of approved costs — leaving you responsible for the other 20%, with no yearly limit on what you could spend.

A Medigap policy steps in to help cover those gaps. Depending on the letter you pick, it may pay your Part A hospital coinsurance, your Part B coinsurance, the first three pints of blood, hospice coinsurance, skilled nursing coinsurance, and more.

Medigap does not cover prescription drugs, dental, vision, hearing, or long-term care. For drugs, you'd add a separate Part D plan.

Why the letters exist

Before standardization, Medigap policies were all over the map, and shopping was a mess. Congress fixed that by requiring insurers to sell plans that fit into standardized "letter" boxes. Today the letters offered to new enrollees are A, B, D, G, K, L, M, and N. Plans C and F are still held by people who were eligible for Medicare before January 1, 2020, but new enrollees generally can't buy them.

Because the benefits inside each letter are set by federal rules, the main differences between two companies selling the same letter come down to price, customer service, and whether the company raises rates over time.

How Medigap fits with the rest of Medicare

Medigap only works with Original Medicare. If you're enrolled in a Medicare Advantage plan (Part C), you can't use a Medigap policy to cover its copays, and it's actually against federal law for someone to sell you one while you're on Advantage — unless you're switching back to Original Medicare.

Dallas is in Dallas County, where residents have many Medicare Advantage and Part D options during the Annual Enrollment Period (Oct. 15 – Dec. 7). But Medigap is different: it isn't tied to that fall window. You can apply any time of year — the catch is that outside of certain protected periods, insurers can use medical underwriting and turn you down or charge more based on your health.

The one enrollment window that matters most

Your Medigap Open Enrollment Period is a six-month window that starts the month you're 65 or older and enrolled in Part B. During those six months, you have a guaranteed right to buy any Medigap policy sold in Texas, at the best available rate for your age, regardless of health history.

Miss that window and, in most cases, insurers can ask health questions and decide whether to sell you a policy. There are a few "guaranteed issue" situations that reopen the door — for example, if a Medicare Advantage plan leaves your area — but the smoothest path is buying during that first six-month window.

Common mistakes to avoid

• Assuming Medigap covers drugs. It doesn't. You'll want a Part D plan too. In 2026, Part D has a $615 maximum deductible and a $2,100 annual out-of-pocket cap, and the old "donut hole" coverage gap is gone.
• Dropping Medigap to try Advantage without a plan. If you leave Medigap and change your mind later, you may face medical underwriting to get it back.
• Comparing only premiums. Two Plan Gs cover the same benefits, but pricing methods (community-rated, issue-age, attained-age) affect how your premium changes as you get older.
• Waiting past your six-month window. The longer you wait, the more health history matters.

Where to get trustworthy help

For the official rules, plan-finder tools, and a side-by-side chart of what each letter covers, start at medicare.gov. You can also call 1-800-MEDICARE (1-800-633-4227), 24 hours a day. For free, unbiased one-on-one counseling in Texas, contact the Health Information, Counseling and Advocacy Program (HICAP), which is the State Health Insurance Assistance Program (SHIP) here — counselors don't sell anything and can walk you through your options.