Medicare Advantage in Napa County, California
14,937 people in Napa County, California were enrolled in Medicare Advantage in October 2026, 46.0% of 32,505 eligible beneficiaries (−1.4 pts since October 2025). Kaiser Foundation Health Plan, Inc. is the largest parent organization with 83% of reported enrollment; 8 parent organizations have 11 or more members and the HHI is 6,929 (highly concentrated). HRSA classifies the county as partly rural. For 2027, 350 members here are in plans that terminate or leave the county. MA plans offered go from 4 to 4.
Parent organizations in Napa County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| Kaiser Foundation Health Plan, Inc. | 12,299 | +499 | 82.7% |
| Imperial Health Plan of California | 1,277 | +1,218 | 8.6% |
| Elevance Health, Inc. | 409 | −237 | 2.7% |
| UnitedHealth Group, Inc. | 349 | −547 | 2.3% |
| Humana Inc. | 209 | −158 | 1.4% |
| California Physicians' Service | 147 | −8 | 1.0% |
| CVS Health Corporation | 100 | −999 | 0.7% |
| St. Joseph Home Care Network | 83 | +24 | 0.6% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 2,967 beneficiaries in Napa County were assigned to 63 Medicare Shared Savings Program ACOs, 25.6% of assignable Original Medicare beneficiaries. Together, roughly 60% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.