Medicare Advantage in Jefferson County, Montana
1,099 people in Jefferson County, Montana were enrolled in Medicare Advantage in October 2026, 28.4% of 3,868 eligible beneficiaries (−0.5 pts since October 2025). Humana Inc. is the largest parent organization with 91% of reported enrollment; 3 parent organizations have 11 or more members and the HHI is 8,400 (highly concentrated). HRSA classifies the county as fully rural. For 2027, 62 members here are in plans that terminate or leave the county, and Health Care Service Corporation leaves. MA plans offered go from 9 to 9.
Parent organizations in Jefferson County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| Humana Inc. | 980 | +263 | 91.4% |
| Health Care Service Corporation | 64 | −44 | 6.0% |
| UnitedHealth Group, Inc. | 28 | −206 | 2.6% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 1,092 beneficiaries in Jefferson County were assigned to 26 Medicare Shared Savings Program ACOs, 60.6% of assignable Original Medicare beneficiaries. Together, roughly 72% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.