What Is Medigap? Medicare Supplement Insurance Explained (2026)
Last reviewed: March 2026 · Source: CMS.gov
In plain English
Medigap is private insurance that fills in the "gaps" that Original Medicare leaves behind — mainly the 20% coinsurance you owe on every Part B medical service. It does not replace Medicare; it works alongside it.
How Medicare's Cost-Sharing Works
Original Medicare pays 80% of covered Part B services (doctor visits, outpatient care, procedures). You pay the remaining 20% — with no annual cap. A $100,000 cancer treatment could leave you with a $20,000 bill. A single hospitalization with complications could trigger the Part A deductible ($1,676 in 2026) plus daily coinsurance for extended stays.
Medigap covers most or all of these remaining costs, depending on which plan letter you choose. Plan G — the most popular — covers everything except the Part B deductible ($257/year).
What Medigap Does and Does Not Cover
✅ What Medigap Covers (Plan G)
- • Part A hospital coinsurance
- • Part A deductible ($1,676)
- • Part A hospice care coinsurance
- • Part B coinsurance (the 20%)
- • Part B excess charges
- • First 3 pints of blood
- • Skilled nursing coinsurance
- • Foreign travel emergency (80%)
❌ What Medigap Does NOT Cover
- • Prescription drugs (need Part D)
- • Dental care
- • Vision care (glasses/contacts)
- • Hearing aids
- • Long-term care
- • Private-duty nursing
- • Part B deductible (Plan G only)
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