Medicare Advantage in Mariposa County, California
703 people in Mariposa County, California were enrolled in Medicare Advantage in October 2026, 13.2% of 5,312 eligible beneficiaries (−0.9 pts since October 2025). Humana Inc. is the largest parent organization with 33% of reported enrollment; 8 parent organizations have 11 or more members and the HHI is 1,975 (highly concentrated). HRSA classifies the county as fully rural. For 2027, 0 members here are in plans that terminate or leave the county. MA plans offered go from 6 to 6.
Parent organizations in Mariposa County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| Humana Inc. | 224 | +72 | 33.0% |
| UnitedHealth Group, Inc. | 143 | −3 | 21.1% |
| Imperial Health Plan of California | 107 | +48 | 15.8% |
| Kaiser Foundation Health Plan, Inc. | 51 | −11 | 7.5% |
| Elevance Health, Inc. | 50 | −81 | 7.4% |
| California Physicians' Service | 40 | 0 | 5.9% |
| CVS Health Corporation | 36 | −93 | 5.3% |
| SANTA CRUZ MONTEREY MERCED SAN BENITO MARIPOSA MAN | 27 | new | 4.0% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 432 beneficiaries in Mariposa County were assigned to 27 Medicare Shared Savings Program ACOs, 13.7% of assignable Original Medicare beneficiaries. Together, roughly 25% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.