Medicare Supplement Insurance (Medigap)

What is Medicare Supplement insurance (Medigap)?

Medigap is private insurance, regulated by both the federal government and the state of Texas, sold alongside Original Medicare (Part A and Part B). It does not replace Original Medicare the way Medicare Advantage does, it pays after Medicare pays, covering some or all of the gap between what Medicare pays and what a provider actually charges.

Every standardized Medigap plan is labeled with a letter, such as Plan G or Plan N. By federal law, Plan G sold by one company must cover the exact same benefits as Plan G sold by any other company, the only things that differ between companies are the premium, customer service, and financial strength. Not every company sells every letter, and not every letter is available to every new enrollee.

This standardization is deliberate: it means comparing Medigap policies in Texas mostly comes down to comparing price and the company behind the policy, rather than trying to compare different benefit packages against each other the way you would with Medicare Advantage plans.

How does Medigap work with Original Medicare?

If you have Original Medicare and a Medigap policy, Medicare pays its share of the Medicare-approved amount for a covered service first, then your Medigap policy pays some or all of the remaining amount, depending on which plan letter you have. There is no provider network, if a doctor or hospital accepts Original Medicare, your Medigap policy works there too, anywhere in the country.

A Medigap policy is guaranteed renewable, meaning the insurance company cannot cancel it just because you get sick or file claims, as long as you keep paying the premium on time and did not make an intentional false statement on your application.

What does Medigap typically cover?

Depending on the plan letter, Medigap can cover Part A coinsurance and hospital costs, Part B coinsurance or copayments, the first three pints of blood each year, Part A hospice care coinsurance, skilled nursing facility coinsurance, and the Part A and Part B deductibles. Some higher-letter plans also cover a portion of emergency care costs during foreign travel, a benefit Original Medicare does not include at all.

Medigap policies sold today do not include prescription drug coverage. If you want drug coverage alongside a Medigap policy, you need a separate, stand-alone Part D plan. Not everyone can buy every plan letter either: Plans C and F (including high-deductible Plan F) are only available to people who first became eligible for Medicare before January 1, 2020. People who became eligible on or after that date can instead choose Plan G, including a high-deductible version of Plan G.

Plan N is a popular middle option: it generally has a lower premium than Plan G, but it pays 100% of Part B coinsurance with some copayments, up to $20 for an office visit and up to $50 for an emergency room visit that does not result in an inpatient admission. Which letter makes sense for you depends on whether you would rather pay more every month for less at the doctor's office, or less every month in exchange for small copays when you use care.

What does Medigap cost?

No federal agency sets or publishes Medigap premiums the way Medicare sets Medicare Advantage plan premiums by county, each private carrier sets its own rates, and a quote depends on your age, whether you use tobacco, your plan letter, and how the carrier rates its policies over time. Because of that, this page does not state a specific premium figure, ask a licensed agent for real quotes from multiple carriers so you can compare.

What is published is the structure some plans use. For 2026, the high-deductible versions of Plan F and Plan G require you to pay $2,950 in Medicare-covered costs yourself before the policy starts paying. Plan K pays 100% of covered services for the rest of the year once you have paid $8,000 out of pocket, and Plan L does the same once you have paid $4,000. On top of any Medigap premium, you still pay your separate Part B premium to Medicare.

Who is Medigap a good fit for?

Medigap tends to fit people who want the widest possible choice of doctors and hospitals nationwide with no network or referral requirements, who travel often within the United States, and who would rather pay a higher, more predictable monthly premium in exchange for lower, more predictable costs when they actually need care.

It may fit less well for someone on a tight monthly budget who rarely needs care, since Medigap premiums are paid every month whether or not you use any services, and it does not include the extra benefits, like dental and vision, that many Medicare Advantage plans bundle in.

When can you enroll in Medigap in Texas?

Your Medigap Open Enrollment Period is a one-time, 6-month window that starts the month you are both 65 or older and enrolled in Part B. During this window, insurance companies in Texas must sell you any Medigap policy they offer, cannot use medical underwriting, and cannot charge you more because of your health history.

Outside that window, Texas allows medical underwriting unless you qualify for a guaranteed issue right, such as losing other coverage (including losing Medicaid due to a change in your financial situation), or losing employer coverage. A guaranteed issue right in Texas generally lasts 63 days from the date your other coverage ends. Texas does not have an annual birthday rule letting existing policyholders switch Medigap plans without underwriting, unlike some other states, so missing your one-time window matters.

Which plan letters you can buy under a guaranteed issue right also depends on when you first became eligible for Medicare: people who became eligible before January 1, 2020 can use a guaranteed issue right to buy Plan A, B, C, F (including high-deductible Plan F), K, or L, regardless of medical history. A standardized Medigap policy is always guaranteed renewable once you have it, the insurance company cannot cancel it later just because you file claims or develop a health condition.

Medicare Supplement vs Medicare Advantage: key differences

Medigap works alongside Original Medicare with no network and a higher, more predictable monthly premium. Medicare Advantage replaces how your Part A and Part B benefits are delivered, usually with a network, a lower or $0 premium, extra benefits like dental and vision, and a yearly out-of-pocket maximum. You cannot have both at the same time. See the full breakdown, including Bexar County 2027 plan and premium data, on the Medicare Advantage page.

How The Insurance Space helps

The Insurance Space is an independent, licensed Medicare agency based in San Antonio, by appointment only. A free review compares real Medigap quotes from multiple carriers against your budget and health needs, at no cost and no obligation to enroll. See local Bexar County Medicare detail on the San Antonio Medicare page, check the official 2027 Medicare & You handbook, or find your exact enrollment window on the turning 65 timeline tool.