2027 Medicare Advantage Plans in Jefferson County, MT

Below is a breakdown of CMS star ratings for Medicare Advantage plans available in Jefferson County, MT for 2027.

* Medicare Advantage star ratings are determined by CMS each year using a standardized 5-star rating system.

• CMS.gov, Medicare Advantage & Special Needs Plan Landscape Source Files — Version: 202609
• CMS.gov, Medicare Part C & D Performance Data — Version: 2026
• CMS.gov, Medicare Advantage & Part D Contract and Enrollment Data — Version: 2026-09

County-level figures shown on this page, including plan counts, enrollment totals, averages, and percentage distributions, reflect standard Medicare Advantage (MA/MAPD) plans only and are derived from CMS datasets using a standardized aggregation methodology.

Data sources and methodology documentation .

• CMS.gov, "Medicare Advantage Plan Fact Sheet" — Last accessed 25 May, 2025
• Medicare.gov, "Your coverage options" — Last accessed 25 May, 2025
• Medicare.gov, "Joining a plan" — Last accessed 25 May, 2025

MedicarePlans.com is an independent, non-government informational resource and is not affiliated with or endorsed by the U.S. Government or the federal Medicare program.

Data provenance documentation is maintained in alignment with the U.S. Core Data for Interoperability (USCDI) Provenance standard .

Page content independently curated and maintained by David W. Bynon, Editorial Steward, using a standardized, data-driven methodology for accurate, non-commercial Medicare plan interpretation and resolution.