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HealthPlan Connect — Licensed Medicare Advisors

Medicare in California: Enrollment Data and Plan Statistics 2026

How California’s 6,938,292Medicare beneficiaries are covered — and how enrollment varies across the state’s 58counties. All figures are from the Centers for Medicare & Medicaid Services (2024).

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6,938,292

Total Medicare beneficiaries

50.7%

On Medicare Advantage

49.3%

On Original Medicare

$202.90

Standard Part B premium (2026)

Medicare Enrollment by County in California

The 15 most-populous counties by Medicare beneficiaries. Click any column heading to sort. Medicare Advantage percentage is the share of each county’s beneficiaries enrolled in an MA or other health plan.

Medicare enrollment by county in California — sortable by area, beneficiaries, or Medicare Advantage percentage
Los Angeles County1,643,99755.8%
San Diego County595,84752.9%
Orange County575,53755.2%
Riverside County429,60562.6%
San Bernardino County334,79566.0%
Santa Clara County298,69949.8%
Sacramento County284,10459.3%
Alameda County267,48251.5%
Contra Costa County219,49152.8%
Ventura County169,91641.6%
San Francisco County156,33049.4%
Fresno County155,22846.8%
San Mateo County138,12850.5%
Kern County130,39146.9%
San Joaquin County123,61952.6%

Key Findings: Medicare in California

  • 1California has 6,938,292 Medicare beneficiaries across 58 counties or county-equivalent areas in the CMS 2024 annual enrollment file.
  • 250.7% of beneficiaries are enrolled in Medicare Advantage or other health plans, compared with 49.3% in Original Medicare.
  • 3Los Angeles County has the largest Medicare beneficiary population among the county rows shown here, with 1,643,997 beneficiaries.
  • 4Medicare Advantage participation varies by county, so statewide percentages should not be treated as plan availability for a specific address.
  • 5Plan availability, provider networks, drug formularies, premiums, and benefits should be verified for the beneficiary's ZIP code and current plan year.

How California Compares to National Averages

Medicare Advantage penetration

California is at 50.7%, 3.3 points below the national average of about 54%.

Plans available

Nationally, the average beneficiary can choose from about 32 Medicare Advantage prescription-drug plans for 2026. The exact number available depends on your county.

Medicare Supplement (Medigap)

Nationally, about 41.9% of Original Medicare beneficiaries carry a Medigap policy (AHIP, 2023). State-by-state Medigap rates are not published in an open dataset, so this figure is national. In California, 49.3% of beneficiaries are in Original Medicare and therefore eligible to buy Medigap.

Explore Medicare by County in California

Use the CMS-backed county enrollment data above as context, then verify current Medicare plan availability, networks, prescriptions, costs, and benefits for your exact ZIP code.

Browse California County Guides

Related Medicare resources for California

Methodology & Sources

Enrollment and county data: Centers for Medicare & Medicaid Services, Medicare Monthly Enrollment, 2024 (data.cms.gov). Figures are 2024 annual counts. Medicare Advantage percentage = (beneficiaries in Medicare Advantage & Other Health Plans ÷ total beneficiaries) × 100. The county table shows the 15 most-populous counties of 58 total.

Part B premium: CMS, 2026 Medicare Parts A & B Premiums and Deductibles. The standard premium is set federally and is the same in every state; higher-income beneficiaries pay an income-related adjustment (IRMAA).

Plan counts and Medigap: KFF, Medicare Advantage 2026 Spotlight (CMS Landscape files); AHIP, The State of Medicare Supplement Coverage, 2023. These are reported as national figures only.

Limitations: Medicare Supplement (Medigap) enrollment and per-county plan counts are not available in an open dataset at the state or county level, so they are not shown per county. Percentages are rounded. Last updated 2026-09-19.

This page is for educational purposes. HealthPlan Connect is not affiliated with or endorsed by CMS or any government agency. Contact a licensed advisor for current plan options in your area.