What Is Medicare Supplement Insurance?
Medicare Supplement insurance — also called Medigap — is one of the most powerful tools available for filling the gaps that Original Medicare leaves behind. If you have ever worried about what you might owe after Medicare pays its share, Medigap is designed to answer that concern. Here is a complete, plain-language explanation of what it is, how it works, and whether it might be the right fit for you.
What Is Medicare Supplement Insurance?
Medicare Supplement insurance — universally known by its nickname, Medigap — is a type of private health insurance designed to work alongside Original Medicare. It does not replace Medicare. Instead it steps in after Medicare pays its share of a covered service and picks up some or all of the remaining costs — the deductibles, coinsurance, and copays that Original Medicare leaves you responsible for.
Here is the core problem Medigap solves: Original Medicare Parts A and B cover a wide range of health care services — but they do not cover everything, and they leave you with real out-of-pocket costs every time you use care. The Part B coinsurance alone is 20% of every Medicare-approved service with no annual cap. A serious illness treated entirely under Original Medicare could leave you owing thousands of dollars. Medigap is the answer to that exposure.
Medigap plans are sold by private insurance companies but are regulated by the federal government. Every plan must follow strict rules about what benefits it provides — which leads to one of Medigap’s most important features: standardization.
📌 How Medigap works in one sentence: Medicare pays first. Then your Medigap plan pays some or all of what is left — so you pay little to nothing out of pocket for covered Medicare services, depending on which plan letter you choose.
The Most Important Feature — Medigap Plans Are Standardized
In most states including Texas, Medigap plans are standardized by the federal government. This means that every insurance company selling a Medigap Plan G must offer exactly the same benefits as every other company selling a Plan G. The plan letter determines the benefits — not the carrier.
What this means for you as a consumer is enormously valuable: you are not comparing apples to oranges when you shop Medigap plans — you are comparing identical products from different sellers. The only differences between a Plan G from one carrier and a Plan G from another are the monthly premium, the company’s financial strength, and its customer service reputation.
This standardization makes Medigap shopping straightforward once you understand the plan letters. You choose the plan letter that covers what you need — then you find the carrier that offers that plan at the best rate with the strongest financial backing.
The Medigap Plan Letters — Which One Is Right for You?
There are several standardized Medigap plan letters available in Texas. The most commonly chosen plans for people turning 65 today are Plan G, Plan N, and High Deductible Plan G. Here is a closer look at each:
Plan G — The Comprehensive Choice
Plan G is the most comprehensive Medigap plan available to new Medicare enrollees today — and the most popular choice for people turning 65 in Texas. It covers virtually everything Medicare does not pay, with one exception: the Part B deductible ($257 in 2026). Once you meet that annual deductible, Plan G covers 100% of your Medicare cost-sharing for the rest of the year.
What Plan G covers:
- Part A hospital deductible ($1,676 per benefit period in 2026) — fully covered
- Part A coinsurance for hospital days 61–90 and lifetime reserve days — fully covered
- Part B coinsurance — 20% of every covered outpatient service — fully covered
- Part B excess charges — what providers charge above Medicare’s approved amount — fully covered
- Skilled nursing facility coinsurance (days 21–100) — fully covered
- Foreign travel emergency coverage — 80% of covered costs up to plan limits
What Plan G does NOT cover: The Part B annual deductible ($257 in 2026). After you pay that once a year, you have essentially $0 out of pocket on covered Medicare services for the rest of the year — at any Medicare-accepting provider in the country.
Best for: People who want maximum predictability, frequent health care users, those with chronic conditions, and anyone who values complete freedom to see any Medicare provider nationwide.
Plan N — Strong Coverage at a Lower Premium
Plan N offers comprehensive Medigap coverage at a lower monthly premium than Plan G — making it an attractive option for people who are generally healthy and willing to accept small copays at each visit in exchange for paying less every month.
How Plan N differs from Plan G:
- You pay a copay of up to $20 for office visits (primary care and specialists)
- You pay a copay of up to $50 for emergency room visits that do not result in inpatient admission
- Plan N does not cover Part B excess charges — the amount some providers charge above Medicare’s approved rate. In Texas, most providers accept Medicare assignment and do not charge excess fees — but it is worth confirming with your specific doctors.
- Like Plan G, Plan N does not cover the Part B annual deductible
Best for: People who are relatively healthy, do not see specialists frequently, and want a lower monthly premium while still maintaining strong coverage and complete provider freedom.
High Deductible Plan G — Maximum Savings on Premiums
High Deductible Plan G offers the same benefits as standard Plan G — but with a very high annual deductible ($2,870 in 2026) before the Medigap coverage kicks in. In exchange for taking on that deductible risk, you pay a dramatically lower monthly premium — sometimes $35 to $80 per month compared to $140 to $200 for standard Plan G.
Under High Deductible Plan G, you pay all Medicare cost-sharing out of pocket until you reach $2,870 in a calendar year. After that, the plan covers 100% of your Medicare cost-sharing for the remainder of the year — the same as standard Plan G.
Best for: People who are in excellent health, rarely use health care services, and are comfortable self-insuring the deductible risk in exchange for very low monthly premiums. The premium savings over standard Plan G can accumulate significantly in healthy years.
Medigap Plan Benefits at a Glance
| Benefit | Plan G | Plan N | HD Plan G |
|---|---|---|---|
| Part A Hospital Deductible | ✅ 100% | ✅ 100% | ✅ After deductible |
| Part A Coinsurance (Days 61+) | ✅ 100% | ✅ 100% | ✅ After deductible |
| Part B Coinsurance (20%) | ✅ 100% | ✅ 100%* | ✅ After deductible |
| Part B Deductible ($257) | ❌ Not covered | ❌ Not covered | ❌ Not covered |
| Part B Excess Charges | ✅ 100% | ❌ Not covered | ✅ After deductible |
| Skilled Nursing Coinsurance | ✅ 100% | ✅ 100% | ✅ After deductible |
| Foreign Travel Emergency | 80% up to limits | 80% up to limits | 80% after deductible |
| Office Visit Copay | $0 | Up to $20/visit | $0 after deductible |
| ER Copay (no admission) | $0 | Up to $50/visit | $0 after deductible |
| Typical Monthly Premium (TX, age 65) | $140 – $200/mo | $80 – $160/mo | $35 – $80/mo |
*Plan N covers Part B coinsurance but you pay a copay of up to $20 for office visits and up to $50 for ER visits that do not result in inpatient admission.
The Freedom Advantage — Any Doctor, Anywhere
One of the most meaningful advantages of Medigap over Medicare Advantage is complete freedom of provider choice. With any Medigap plan, you can see any doctor, specialist, or hospital in the United States that accepts Medicare — with no network restrictions, no referrals required, and no prior authorizations for covered services.
This freedom matters in several specific situations:
- Traveling or living in multiple locations: Medigap follows you everywhere. Whether you are in McAllen, visiting family in Houston, or wintering in Florida, your coverage is the same at any Medicare provider nationwide.
- Accessing major medical centers: MD Anderson Cancer Center, Mayo Clinic, Cleveland Clinic, UT Southwestern — all accept Medicare, and all are accessible to Medigap enrollees with no network barriers or out-of-network charges.
- Chronic conditions requiring specialist access: If you see multiple specialists regularly, the ability to see any of them without referrals or network checks removes significant friction from your care.
- Keeping your existing doctors: As long as your doctors accept Medicare, they accept your Medigap plan — regardless of which carrier issued it or which plan letter you chose.
The Medigap Open Enrollment Window — Your Most Important Timing Consideration
In Texas, there is a specific window when you are guaranteed the right to purchase any Medigap plan from any carrier at the best available rate — regardless of your health history. This is called your Medigap Open Enrollment Period, and it is one of the most important timing elements in all of Medicare.
Your Medigap Open Enrollment Period begins the month you are both age 65 or older AND enrolled in Medicare Part B, and it lasts for six months. During this window, Medigap insurance companies in Texas must:
- Sell you any plan they offer — you cannot be turned down
- Charge you the same premium they charge any other person your age — regardless of your health conditions
- Not impose waiting periods for pre-existing conditions (with limited exceptions)
After this six-month window closes, Texas follows federal rules that allow insurance companies to use medical underwriting — evaluating your health history and potentially denying your application, charging you a higher premium, or excluding pre-existing conditions from coverage. There are some guaranteed issue exceptions, but they are limited and specific.
The six-month Medigap Open Enrollment Period is the only time most people in Texas are guaranteed the right to buy any Medigap plan at standard rates regardless of health. If you enroll in Medicare Advantage first and later decide you want Medigap — perhaps because your health has changed — you may find that you cannot get a Medigap plan at an affordable rate, or at all. This asymmetry is one of the most important reasons to carefully consider Medigap at age 65, even if Medicare Advantage looks appealing in the short term.
What Medigap Does Not Cover
Medigap fills the gaps in Medicare — but it only covers costs related to services that Medicare itself covers. It does not create new coverage for things Medicare does not cover at all. Specifically, Medigap does not cover:
🦷 Routine Dental
Cleanings, fillings, crowns, dentures, and extractions are not covered by Medicare or Medigap. A separate dental plan is needed.
👁️ Routine Vision
Eye exams for glasses and contact lenses are not covered. A separate vision plan or Medicare Advantage with vision benefits is needed.
👂 Hearing Aids
Hearing exams and hearing aids are not covered by Medicare or Medigap. A separate hearing benefit or Medicare Advantage plan is needed.
💊 Prescription Drugs
Medigap does not include drug coverage. A standalone Medicare Part D plan must be added separately for prescription coverage.
🏠 Long-Term Care
Custodial care — help with daily living activities in a nursing home or at home — is not covered by Medicare or Medigap.
🌍 International Care
Plans G and N include limited foreign travel emergency coverage — but routine care outside the U.S. is not covered by Medicare or Medigap.
What Medigap Looks Like in Real Life
Carlos, 67, lives in McAllen and has Original Medicare plus a Medigap Plan G. He is treated for a cardiac condition that requires a hospitalization, follow-up specialist visits, and ongoing outpatient care over the course of a year.
His health care use that year:
• Inpatient hospital stay (4 days) — Medicare-approved cost: $12,000
Medicare pays 80% after deductible: $10,324. Plan G pays the Part A deductible ($1,676) and remaining balance.
Carlos pays: $0
• 8 cardiologist visits — Medicare-approved cost: $1,600 total
Medicare pays 80% ($1,280). Plan G pays the 20% coinsurance ($320).
Carlos pays: $0 (after his $257 Part B annual deductible)
• Echocardiogram and stress test — Medicare-approved cost: $800
Medicare pays 80% ($640). Plan G pays the 20% coinsurance ($160).
Carlos pays: $0
Carlos’s total out-of-pocket medical costs for the year: $257 (Part B deductible) + his Plan G premium ($150/mo × 12 = $1,800) + Part B premium ($185 × 12 = $2,220) + Part D drug plan = approximately $4,500 total for the year — despite having a major cardiac hospitalization and months of specialist care.
Without Medigap, Carlos could have owed $3,000 to $5,000+ in Medicare cost-sharing on top of his premiums.
Is Medigap Right for You?
Medicare Supplement insurance is likely the right fit if you:
- Want predictable, low out-of-pocket costs regardless of how much health care you use
- Have chronic conditions or expect to use health care services frequently
- Want complete freedom to see any Medicare-accepting provider — no networks, no referrals
- Travel frequently or spend time in multiple states and need nationwide coverage
- Are in your Medigap Open Enrollment Period and want to lock in guaranteed issue rights while you have them
- Are willing to pay a higher monthly premium in exchange for very low out-of-pocket costs at the point of care
Medigap may not be the best fit if you are primarily motivated by minimizing monthly premiums, if you are healthy and rarely use health care, or if the extra benefits of Medicare Advantage — dental, vision, hearing, fitness — would provide meaningful value you cannot easily replicate through separate plans.
Want to See What Medigap Plans Are Available in Your Area?
I compare Medigap plans from multiple highly rated carriers across the Rio Grande Valley — showing you which plan letter fits your situation and which carrier offers the best rate for that coverage. The comparison is always free, always in plain language, and always honest about the trade-offs. Serving families across Brownsville, Harlingen, McAllen, and all of South Texas in English and Spanish.
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