How is Medicare Advantage developing in Riverside County, California?
Data through Plan year 2026, with 2023–2026 penetration history · Updated May 1, 2026
static extract
Riverside County's MA penetration is 63.1% — above the 57.8% national share by 5.3 points, with 0.328M MA enrollees of 0.52M Medicare beneficiaries as of Plan year 2026, with 2023–2026 penetration history. It ranks 2 of 10 California counties by penetration.
+0.77 pts
YoY velocity
prior year → Plan year 2026, with 2023–2026 penetration history
4
Carriers competing
Plan year 2026, with 2023–2026 penetration history
Penetration trajectory, 2023–2026
MA share of all Medicare beneficiaries in the county, plan years 2023–2026. Plan year 2026, with 2023–2026 penetration history.
Market structure in Riverside County
| Top carrier | UHC |
| Carriers competing | 4 |
| MA enrollees | 0.328M |
| Total Medicare beneficiaries | 0.52M |
| D-SNP share of MA | 16% |
| Market type | Switcher (50%+ penetration) |
County carrier and D-SNP figures are the CPSC county extract (Plan year 2026, with 2023–2026 penetration history). Carrier-level enrollment and stars are tracked at the state level.
So what / Now what
Riverside County is a switcher market at 63.1% penetration — expansion means winning members from incumbent MA plans on benefits, network, and brand.
- Compare to the rest of California on the state page.
- Check 2026 plan exits for orphaned membership contestable in California.
- Sales teams: see how California ranks on the growth runway index and which competitive facts apply on the carrier battlecards.
Neighboring California counties
Provenance — County-level MA market snapshot (76 tracked counties)
- Source file
- CMS MA Enrollment by State/County/Plan (CPSC monthly files)
- Vintage
- Plan year 2026, with 2023–2026 penetration history
- Last updated
- May 1, 2026
- Refresh cadence
- Monthly (pipeline pending; currently a curated extract)
- Method
- Penetration, D-SNP share, carrier count and top carrier per county compiled from CPSC files for 76 high-signal counties.
- Known limitations
- Covers 76 tracked counties, not all ~3,100. Velocity = simple YoY penetration point change.