Original Medicare (Parts A and B) only covers about 80% of your medical expenses — leaving the remaining 20% as deductibles, coinsurance, and copayments that you pay out of pocket. A Medicare Supplement (Medigap) plan is private insurance sold by licensed insurance companies to help cover those gaps, giving you more predictable healthcare costs and peace of mind.
What Medicare Doesn’t Cover
Before understanding why a Medigap plan matters, it helps to see what Original Medicare actually leaves behind:
- Hospital deductible: $1,736 per benefit period (2026)
- Days 61–90 coinsurance: $434/day
- Lifetime reserve days: $868/day
- Skilled nursing (days 21–100): $217/day
- No coverage after 150 days
- Annual deductible: $283 (2026)
- 20% coinsurance on all approved services — no cap
- No out-of-pocket maximum
- Excess charges from non-assignment doctors
- No foreign travel emergency coverage
The 20% Part B coinsurance has no annual cap. A $100,000 hospital stay could leave you with $20,000 in out-of-pocket costs under Original Medicare alone. A Medigap plan eliminates or sharply limits that exposure.
How Medigap Plans Work
Plan Benefit Comparison Chart
The chart below shows exactly which Medicare cost-sharing gaps each standardized plan letter covers. Use it to understand what each plan includes before comparing premiums.
* Plans C and F are only available to beneficiaries who became Medicare-eligible before January 1, 2020. † Plan N pays Part B coinsurance but you may owe up to $20 copay for office visits and up to $50 for ER visits not resulting in hospital admission.
The Most Popular Plans for New Enrollees
Plan G
The most widely purchased plan for new enrollees. Covers everything except the $283 Part B deductible. After that one annual cost, all Medicare-approved charges are covered in full.
Plan N
A strong value alternative to Plan G. Slightly lower premium in exchange for up to $20 office visit copays and up to $50 ER copays. Does not cover excess charges.
High-Deductible Plan G
Same benefits as Plan G after a $2,870 annual deductible (2026). Premiums are 40–60% lower. Best for healthy beneficiaries who want catastrophic protection at minimal cost.
Medigap vs. Medicare Advantage: The Key Difference
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