Medicare Advantage in Lewis and Clark County, Montana
5,535 people in Lewis and Clark County, Montana were enrolled in Medicare Advantage in October 2026, 29.5% of 18,743 eligible beneficiaries (+0.1 pts since October 2025). Humana Inc. is the largest parent organization with 81% of reported enrollment; 6 parent organizations have 11 or more members and the HHI is 6,724 (highly concentrated). HRSA classifies the county as partly rural. For 2027, 664 members here are in plans that terminate or leave the county, and Health Care Service Corporation leaves. MA plans offered go from 13 to 13.
Parent organizations in Lewis and Clark County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| Humana Inc. | 4,448 | +902 | 80.8% |
| Health Care Service Corporation | 713 | −714 | 13.0% |
| UnitedHealth Group, Inc. | 253 | −20 | 4.6% |
| CVS Health Corporation | 63 | +7 | 1.1% |
| Elevance Health, Inc. | 14 | −3 | 0.3% |
| Blue Cross Blue Shield of Michigan Mutual Ins. Co. | 12 | 0 | 0.2% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 6,578 beneficiaries in Lewis and Clark County were assigned to 64 Medicare Shared Savings Program ACOs, 73.6% of assignable Original Medicare beneficiaries. Together, roughly 81% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.