Medicare Advantage in Riverside County, CA

MA enrolled

285,880

MA enrolled

Medicare eligibles

450,293

Medicare eligibles

MA penetration

63.5%

MA penetration

2026 plans on offer

91

2026 plans on offer

Enrollment and eligibles: CMS MA State/County Penetration, report month 2026-04-01. County keys: FIPS 06065, SSA 05430. Plans on offer: CMS 2026 Landscape, MA + SNP categories.

Who holds the market

Parent organizations by MA enrollment in the county, April 2026. Standalone Part D plans are excluded. Share = the parent's enrollees divided by the county's MA enrolled from the penetration file (the two CMS files can differ slightly; the denominator is stated, not assumed). A cell CMS suppressed (under 11 members) is counted as a bounded unknown, never as zero.

What is on offer for 2026

From the CMS Landscape file for plan year 2026: distinct plans by type, how many carry a $0 consolidated premium, and the range of in-network maximum out-of-pocket (MOOP). A published premium of "Not Applicable" is left out of the premium statistics, not treated as $0.

lowest premium

$0

lowest premium

median premium (n=86)

$0

median premium (n=86)

lowest MOOP

$199

lowest MOOP

highest MOOP

$9,250

highest MOOP

The plans people are in

The largest plans in the county by April 2026 enrollment, with their 2026 premium and MOOP as published. Enrollment is the April 2026 CPSC file; premium and MOOP are the 2026 Landscape; the two describe different moments and are labelled so.

Star Ratings of the contracts offered here

CMS rates contracts, not counties or plans. The overall Star Rating below is the contract's rating as carried in the 2026 Landscape file (which reflects the July 2026 update); it applies to every plan under that contract nationally and says nothing county-specific.

Method and limits

• Enrollment, eligibles and penetration are the CMS MA State/County Penetration file for 2026-04-01; the carrier mix is the CMS Monthly Enrollment by Contract/Plan/State/County (CPSC) file for the same month, restricted to MA contracts (H, R and E contract numbers; standalone Part D S-contracts excluded).
• CMS suppresses any cell under 11 members. Those cells are shown as a range and excluded from shares; they are never zero. Parent rollups use the parent organization CMS publishes, not name matching.
• Plans on offer are the CMS 2026 MA/Part D Landscape file, MA and SNP categories, counted as distinct contract-plan pairs. Premiums and MOOP are the published strings cast to numbers; "Not Applicable" is excluded from statistics.
• Year-over-year compares the same report month one year earlier. Plan year, report month and retrieval date are three different clocks and are labelled separately.
• A negotiated benefit or premium here is what a plan publishes, not what any individual pays; this page is not eligibility or enrollment advice.
• Data from the Centers for Medicare & Medicaid Services public files, cleaned and joined by Vlada. CMS does not endorse this page or Vlada Health. County identity is the CMS SSA county code (05430); the FIPS code (06065) is shown for reference and can cover more than one SSA cell.

Receipts

Every section above is one read-only query over the Vlada substrate, run through the same tool an agent would call. The query, the engine's query id, the response hash and the bytes scanned are recorded so the numbers can be re-run.

SELECT fips, ssa, state_name, county_name, eligibles, enrolled, penetration FROM medicare_silver.ma_state_county_penetration WHERE report_month = DATE '2026-04-01' AND enrolled IS NOT NULL ORDER BY enrolled DESC LIMIT 10

SELECT ssa, eligibles, enrolled, penetration FROM medicare_silver.ma_state_county_penetration WHERE report_month = DATE '2025-04-01' AND ssa IN ('05200', '03060', '45610', '14141', '10120', '05400', '05470', '05430', '33590', '10050')

SELECT county_ssa, parent_org_raw, SUM(enrollment_count) AS enrolled, COUNT(*) AS plan_rows, SUM(CASE WHEN enrollment_count IS NULL THEN 1 ELSE 0 END) AS suppressed_rows, SUM(enrollment_lower_bound) AS lower_bound, SUM(enrollment_upper_bound) AS upper_bound FROM medicare_silver.enrollment_monthly_county WHERE report_month = DATE '2026-04-01' AND contract_id NOT LIKE 'S%' AND county_ssa IN ('05470', '05430', '33590', '10050') GROUP BY county_ssa, parent_org_raw HAVING SUM(enrollment_count) >= 500 ORDER BY county_ssa, enrolled DESC LIMIT 2000

SELECT county_ssa, COUNT(*) AS parents, SUM(lower_bound) AS lower_bound, SUM(upper_bound) AS upper_bound FROM (SELECT county_ssa, parent_org_raw, SUM(enrollment_count) AS enrolled, SUM(enrollment_lower_bound) AS lower_bound, SUM(enrollment_upper_bound) AS upper_bound FROM medicare_silver.enrollment_monthly_county WHERE report_month = DATE '2026-04-01' AND contract_id NOT LIKE 'S%' AND county_ssa IN ('05200', '03060', '45610', '14141', '10120', '05400', '05470', '05430', '33590', '10050') GROUP BY county_ssa, parent_org_raw) t WHERE enrolled IS NULL OR enrolled < 500 GROUP BY county_ssa LIMIT 2000

SELECT contract_id, plan_id, segment_id, plan_name, plan_type, parent_org_name, snp_type, category, consolidated_premium, moop_in_network, overall_star_rating FROM medicare_silver.fact_ma_landscape WHERE report_year = 2026 AND category IN ('MA','SNP') AND state = 'CA' AND county = 'Riverside' ORDER BY contract_id, plan_id, segment_id LIMIT 2000

SELECT contract_id, plan_id, parent_org_raw, enrollment_count, enrollment_lower_bound, enrollment_upper_bound FROM medicare_silver.enrollment_monthly_county WHERE report_month = DATE '2026-04-01' AND contract_id NOT LIKE 'S%' AND county_ssa = '05430' ORDER BY enrollment_count DESC NULLS LAST LIMIT 45

Generated 2026-09-15 · cohort rule: the 10 largest counties by MA enrollment at the 2026-04-01 report month, SSA-keyed · run these queries yourself · get_market_share · get_landscape