Medicare Advantage in Williamson County, Texas
50,162 people in Williamson County, Texas were enrolled in Medicare Advantage in October 2026, 47.3% of 105,947 eligible beneficiaries (−0.4 pts since October 2025). UnitedHealth Group, Inc. is the largest parent organization with 47% of reported enrollment; 13 parent organizations have 11 or more members and the HHI is 3,098 (highly concentrated). For 2027, 3,418 members here are in plans that terminate or leave the county, and Health Care Service Corporation leaves. MA plans offered go from 43 to 35.
Parent organizations in Williamson County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| UnitedHealth Group, Inc. | 23,290 | −1,133 | 46.6% |
| Humana Inc. | 13,904 | +3,021 | 27.8% |
| Baylor Scott & White Health | 4,504 | +612 | 9.0% |
| CVS Health Corporation | 3,102 | −824 | 6.2% |
| Health Care Service Corporation | 2,636 | −297 | 5.3% |
| Devoted Health, Inc. | 1,503 | +682 | 3.0% |
| Centene Corporation | 558 | −343 | 1.1% |
| Elevance Health, Inc. | 239 | +1 | 0.5% |
| Blue Cross Blue Shield of Michigan Mutual Ins. Co. | 132 | −8 | 0.3% |
| First Sacramento Capital Funding LLC | 80 | +17 | 0.2% |
| California Physicians' Service | 32 | 0 | under 0.1% |
| Regency ISNP Holdings LLC | 26 | +14 | under 0.1% |
| Highmark Health | 20 | +2 | 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, 21,282 beneficiaries in Williamson County were assigned to 220 Medicare Shared Savings Program ACOs, 55.5% of assignable Original Medicare beneficiaries. Together, roughly 77% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.