Medicare Advantage in Jefferson County, Idaho
1,999 people in Jefferson County, Idaho were enrolled in Medicare Advantage in October 2026, 36.7% of 5,449 eligible beneficiaries (−13.1 pts since October 2025). UnitedHealth Group, Inc. is the largest parent organization with 65% of reported enrollment; 6 parent organizations have 11 or more members and the HHI is 4,672 (highly concentrated). HRSA classifies the county as fully rural. For 2027, 167 members here are in plans that terminate or leave the county. MA plans offered go from 11 to 11.
Parent organizations in Jefferson County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| UnitedHealth Group, Inc. | 1,285 | +420 | 64.8% |
| Gemstone Holdings, Inc. | 397 | −1,107 | 20.0% |
| Molina Healthcare, Inc. | 141 | −29 | 7.1% |
| Humana Inc. | 81 | +44 | 4.1% |
| Fenyx Health Holdings, Inc. | 54 | new | 2.7% |
| CVS Health Corporation | 26 | +2 | 1.3% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 1,234 beneficiaries in Jefferson County were assigned to 19 Medicare Shared Savings Program ACOs, 64.3% 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.