Medicare
What is Medicare Supplement insurance?
Medicare Supplement insurance (also called Medigap) is private health insurance that fills the gaps in Original Medicare. Original Medicare pays about 80% of covered costs — Medigap pays some or all of the remaining 20%. Plan G is the most popular choice for new enrollees because it covers everything Medicare covers except the Part B deductible ($257 in 2026). You pay a monthly premium to the private insurer; in return, you have predictable, low out-of-pocket costs.
Key Points
- Medigap fills the 20% gap Original Medicare doesn't cover
- 10 standardized plans — same benefits regardless of which company sells them
- Plan G is the most popular for new enrollees in 2026
- You must have Medicare Parts A and B to buy a Medigap plan
- Premiums vary significantly by company, age, and state — always compare
- Medigap does NOT cover prescription drugs — you need a separate Part D plan