Medicare Advantage in Santa Clara County, California
160,442 people in Santa Clara County, California were enrolled in Medicare Advantage in October 2026, 50.9% of 315,377 eligible beneficiaries (−0.04 pts since October 2025). Kaiser Foundation Health Plan, Inc. is the largest parent organization with 55% of reported enrollment; 19 parent organizations have 11 or more members and the HHI is 3,383 (highly concentrated). HRSA classifies the county as partly rural. For 2027, 9,207 members here are in plans that terminate or leave the county, and UnitedHealth Group, Inc., Molina Healthcare, Inc., Health Plan of San Mateo leave. MA plans offered go from 26 to 19.
Parent organizations in Santa Clara County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| Kaiser Foundation Health Plan, Inc. | 87,852 | +3,093 | 54.9% |
| Alignment Healthcare USA, LLC | 23,451 | +2,892 | 14.6% |
| SANTA CLARA COUNTY HEALTH AUTHORITY | 11,748 | +430 | 7.3% |
| Elevance Health, Inc. | 11,484 | −4,348 | 7.2% |
| SCAN Group | 8,435 | +5,894 | 5.3% |
| UnitedHealth Group, Inc. | 6,616 | −1,325 | 4.1% |
| Astiva Health Holdings Incorporated | 2,598 | +1,614 | 1.6% |
| CVS Health Corporation | 2,050 | −2,952 | 1.3% |
| Imperial Health Plan of California | 1,743 | +632 | 1.1% |
| Molina Healthcare, Inc. | 1,699 | −1,554 | 1.1% |
| California Physicians' Service | 1,226 | −132 | 0.8% |
| On Lok, Inc. | 399 | +42 | 0.2% |
| WelbeHealth LLC. | 244 | +67 | 0.2% |
| Humana Inc. | 194 | +77 | 0.1% |
| Health Plan of San Mateo | 148 | −54 | under 0.1% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 35,956 beneficiaries in Santa Clara County were assigned to 192 Medicare Shared Savings Program ACOs, 39.5% of assignable Original Medicare beneficiaries. Together, roughly 70% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.