Medicare Advantage in Ada County, Idaho
59,754 people in Ada County, Idaho were enrolled in Medicare Advantage in October 2026, 55.4% of 107,808 eligible beneficiaries (−3.4 pts since October 2025). UnitedHealth Group, Inc. is the largest parent organization with 39% of reported enrollment; 16 parent organizations have 11 or more members and the HHI is 2,499 (highly concentrated). For 2027, 14,698 members here are in plans that terminate or leave the county, and Trinity Health Corporation leaves. MA plans offered go from 23 to 19.
Parent organizations in Ada County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| UnitedHealth Group, Inc. | 23,321 | −3,422 | 39.1% |
| Gemstone Holdings, Inc. | 13,289 | −9,275 | 22.3% |
| Trinity Health Corporation | 11,267 | +9,467 | 18.9% |
| Humana Inc. | 5,350 | +2,541 | 9.0% |
| Molina Healthcare, Inc. | 2,533 | −260 | 4.3% |
| PacificSource | 1,938 | +1,035 | 3.3% |
| CVS Health Corporation | 647 | +27 | 1.1% |
| Cambia Health Solutions, Inc. | 517 | −1,416 | 0.9% |
| Elevance Health, Inc. | 343 | +12 | 0.6% |
| California Physicians' Service | 124 | +2 | 0.2% |
| Mitchell Family Office | 94 | +50 | 0.2% |
| Fenyx Health Holdings, Inc. | 56 | new | under 0.1% |
| Blue Cross Blue Shield of Michigan Mutual Ins. Co. | 50 | −2 | under 0.1% |
| Health Care Service Corporation | 21 | +2 | under 0.1% |
| Kaiser Foundation Health Plan, Inc. | 16 | −4 | 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, 4,783 beneficiaries in Ada County were assigned to 135 Medicare Shared Savings Program ACOs, 17.5% of assignable Original Medicare beneficiaries. Together, roughly 63% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.