Original Medicare is a great foundation. But here's the thing most people don't realize until they actually need care: it only pays about 80% of your medical costs.
That other 20%? It falls on you. And unlike most insurance, Original Medicare has no annual out-of-pocket maximum. That means a serious illness, a prolonged hospital stay, or a complicated surgery could leave you with bills that keep climbing with no cap in sight. That's exactly what a Medicare Supplement plan — also called Medigap — is designed to fix.
What Is a Medicare Supplement Plan?
A Medicare Supplement plan is a private insurance policy that works alongside Original Medicare — not instead of it. When Medicare pays its portion of a covered service, your Medigap plan steps in to cover some or all of what's left over.
That can include the Part A hospital deductible ($1,736 per benefit period in 2026), the Part B 20% coinsurance on doctor visits and outpatient services, skilled nursing facility coinsurance, and more.
What Medigap does not cover: prescription drugs (you'll need a separate Part D plan), routine dental, vision, hearing, or long-term custodial care.
Meet Judith
Judith is 68 and lives in Torrance. She'd been on Original Medicare for three years and never thought much about the 20% she owed on covered services — her health had been good and the bills were manageable.
Then she needed a knee replacement. Between the surgery, anesthesia, post-operative appointments, and physical therapy, her 20% share came to just over $4,200. She hadn't enrolled in a Medigap plan during her one-time guaranteed window, so she had to go through health underwriting. She eventually found a plan, but it was more expensive than it would have been earlier.
The lesson: the best time to get a Medigap plan is the moment you're first eligible.
The Medigap Open Enrollment Window: Don't Miss It
You get one guaranteed window — use it. Your Medigap open enrollment period begins the month you're both 65 or older AND enrolled in Medicare Part B. It lasts exactly six months. During that window, insurance companies cannot deny you a Medigap plan or charge you more based on any pre-existing health conditions. Once it closes, that protection is gone. Insurers can require health underwriting, and they may decline your application entirely.
This window doesn't come back. If you're approaching 65, this should be on your radar alongside everything else in your Medicare planning.
The Main Medigap Plans
Every Medigap plan is standardized by the federal government. A Plan G from one insurance company covers exactly the same benefits as a Plan G from another. The only things that differ are the monthly premium and the quality of customer service.
| Plan | What It Covers | Best Fit |
|---|---|---|
| Plan G | Covers nearly everything Original Medicare doesn't — Part A deductible and coinsurance, Part B coinsurance, skilled nursing, foreign travel emergency. Only gap: the Part B deductible ($283 in 2026). | People who want comprehensive, predictable coverage and are newly eligible for Medicare. |
| Plan N | Same core coverage as Plan G, but with small copays for some doctor visits ($20) and ER visits ($50). Lower monthly premiums in exchange. | People in good health who want solid coverage at a lower premium and are comfortable with occasional small copays. |
| Plan F | The most complete plan — covers even the Part B deductible. No longer available to new enrollees, but grandfathered for those eligible before January 1, 2020. | Only available if you were Medicare-eligible before 2020. If you have it, you can keep it. |
| Plan A | Basic Medigap benefits only — Part B coinsurance and some Part A costs. Does not cover the Part A deductible. | People who want minimal gap coverage at the lowest premium. |
For most people enrolling in Medicare today, the decision comes down to Plan G vs. Plan N. Plan G offers more complete protection; Plan N lowers your monthly premium in exchange for small copays.
What Does Medigap Cost?
Because benefits are standardized, the only reason to shop multiple companies is price. And prices can vary significantly for the exact same plan.
- Plan G: typically $100 – $300/month depending on age, location, and insurer
- Plan N: typically $80 – $250/month
Pricing is also affected by which rating method a company uses:
- Community-rated: Everyone pays the same premium regardless of age.
- Issue-age-rated: Your premium is based on your age when you first enroll and stays relatively stable over time.
- Attained-age-rated: Your premium increases as you get older.
Comparing prices across companies is always worth it — you're getting identical benefits, so there's no reason to pay more than you have to.
Medigap vs. Medicare Advantage: The Core Trade-Off
| Feature | Medicare Supplement (Medigap) | Medicare Advantage (Part C) |
|---|---|---|
| Provider access | Any doctor or hospital that accepts Medicare — nationwide | Network-based (HMO or PPO) — out-of-network costs more |
| Out-of-pocket costs | Minimal after premium — most costs are covered | Copays, coinsurance, and an annual OOP maximum |
| Prescription drugs | Not included — requires a separate Part D plan | Usually included in the plan |
| Extra benefits | None beyond medical cost coverage | May include dental, vision, hearing, fitness |
| Travel coverage | Some plans cover foreign travel emergencies | Emergency care typically U.S.-based |
Medigap is often the better fit for people who travel, have complex health needs, or want the freedom to see any Medicare-accepting provider without network restrictions. Medicare Advantage tends to work well for people who want one bundled plan, extra perks, and lower upfront costs.
Compare Medigap plans in your area — for free.
Because Medigap benefits are standardized, the only thing that varies between insurers is price. We'll compare your options side by side so you don't overpay for identical coverage.
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