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MA Enrollment Explorer / States / California

Medicare Advantage in California: enrollment, penetration and market share

3,761,611 people in California were enrolled in Medicare Advantage in October 2026. 51.5% of the state's 7,301,183 eligible Medicare beneficiaries are in Medicare Advantage, −0.2 pts since October 2025. Kaiser Foundation Health Plan, Inc. is the largest parent organization with 41% of reported enrollment; 73 parent organizations have 11 or more members, and the market's HHI is 2,051 (highly concentrated). Through the 2026 Annual Election Period (December to February), reported MA enrollment in California changed by −673 (−0.0%).

51.5%MA penetration, October 2026
3.76MMA enrollees
73parent organizations (11+ members)
2,051HHI, highly concentrated
Open California on the market mapMSSP ACOs in California

Parent organizations in California

Parent organizationMembersChangeShareShare change
Kaiser Foundation Health Plan, Inc.1,532,145+57,45740.8%+0.7 pts
SCAN Group436,697+132,98011.6%+3.4 pts
UnitedHealth Group, Inc.381,030−101,20110.2%−3.0 pts
Elevance Health, Inc.282,171−34,5827.5%−1.1 pts
Alignment Healthcare USA, LLC238,066+44,8316.3%+1.1 pts
Humana Inc.146,212+9,5793.9%+0.2 pts
California Physicians' Service117,206−12,3723.1%−0.4 pts
CVS Health Corporation100,044−37,4232.7%−1.1 pts
Centene Corporation81,458−30,0822.2%−0.9 pts
Molina Healthcare, Inc.62,366−44,3531.7%−1.2 pts
Astiva Health Holdings Incorporated54,204+16,1681.4%+0.4 pts
Clever Care Health Plan, Inc.53,392+24,0111.4%+0.6 pts
Imperial Health Plan of California53,361+28,6481.4%+0.7 pts
INLAND EMPIRE HEALTH PLAN38,265−491.0%−0.02 pts
Local Initiative Health Authority for LA County30,632+1,0210.8%+0.01 pts
Sharp Healthcare19,855+2,4680.5%+0.1 pts
Orange County Health Authority19,417+1,0510.5%+0.02 pts
SANTA CLARA COUNTY HEALTH AUTHORITY11,885+4350.3%+0.00 pts
The Regents of the University of California11,873+4,7450.3%+0.1 pts
Community Health Group10,829+1,4960.3%+0.03 pts

Change and share change are since October 2025. Shares are of reported enrollment in the CMS State/County/Contract file.

Counties

CountyMA enrolleesPenetrationLeading parent
Los Angeles County987,69057.1%Kaiser Foundation Health Plan, Inc. 35%
Orange County341,72055.9%Kaiser Foundation Health Plan, Inc. 26%
San Diego County338,55153.6%Kaiser Foundation Health Plan, Inc. 34%
Riverside County289,81263.3%Kaiser Foundation Health Plan, Inc. 32%
San Bernardino County239,10667.2%Kaiser Foundation Health Plan, Inc. 35%
Sacramento County187,59162.9%Kaiser Foundation Health Plan, Inc. 59%
Santa Clara County160,44250.9%Kaiser Foundation Health Plan, Inc. 55%
Alameda County148,38252.8%Kaiser Foundation Health Plan, Inc. 73%
Contra Costa County120,69052.2%Kaiser Foundation Health Plan, Inc. 76%
San Francisco County83,22051.8%Kaiser Foundation Health Plan, Inc. 44%
Fresno County80,05948.9%Kaiser Foundation Health Plan, Inc. 29%
San Mateo County73,79550.7%Kaiser Foundation Health Plan, Inc. 59%
Ventura County73,21641.1%Kaiser Foundation Health Plan, Inc. 41%
San Joaquin County72,27955.5%Kaiser Foundation Health Plan, Inc. 48%
Sonoma County66,26053.7%Kaiser Foundation Health Plan, Inc. 79%
Kern County65,07147.5%Kaiser Foundation Health Plan, Inc. 32%
Placer County58,85657.2%Kaiser Foundation Health Plan, Inc. 61%
Stanislaus County57,28858.9%Alignment Healthcare USA, LLC 32%
Solano County52,26855.7%Kaiser Foundation Health Plan, Inc. 85%
Marin County29,55845.3%Kaiser Foundation Health Plan, Inc. 81%
Tulare County26,79337.1%Humana Inc. 33%
El Dorado County22,04341.7%Kaiser Foundation Health Plan, Inc. 63%
Yolo County19,32451.6%Kaiser Foundation Health Plan, Inc. 43%
San Luis Obispo County17,86523.9%Alignment Healthcare USA, LLC 32%
Santa Barbara County17,60220.2%UnitedHealth Group, Inc. 44%
Santa Cruz County15,36825.6%Kaiser Foundation Health Plan, Inc. 39%
Napa County14,93746.0%Kaiser Foundation Health Plan, Inc. 83%
Imperial County14,28437.2%Champion Health Plans-USA, LLC. 30%
Madera County13,86549.8%Kaiser Foundation Health Plan, Inc. 45%
Monterey County12,32116.2%Montage Health 68%
Merced County12,18528.3%Imperial Health Plan of California 38%
Kings County7,58237.8%Elevance Health, Inc. 26%
Nevada County5,85418.2%UnitedHealth Group, Inc. 66%
Butte County5,53111.3%Elevance Health, Inc. 34%
Shasta County3,6587.4%Elevance Health, Inc. 35%
Amador County3,60728.6%Kaiser Foundation Health Plan, Inc. 47%
Yuba County2,91720.1%Kaiser Foundation Health Plan, Inc. 48%
Humboldt County2,6868.5%Imperial Health Plan of California 33%
Mendocino County2,63110.8%UnitedHealth Group, Inc. 72%
Calaveras County2,02313.9%Humana Inc. 38%
Lake County1,86710.4%UnitedHealth Group, Inc. 73%
San Benito County1,70114.8%Imperial Health Plan of California 61%
Tuolumne County1,68410.0%Elevance Health, Inc. 27%
Sutter County1,4947.9%Elevance Health, Inc. 46%
Tehama County1,4579.5%Elevance Health, Inc. 47%
Mariposa County70313.2%Humana Inc. 33%
Plumas County63910.2%Humana Inc. 39%
Siskiyou County5834.2%UnitedHealth Group, Inc. 37%
Inyo County54010.9%UnitedHealth Group, Inc. 44%
Lassen County5229.1%Humana Inc. 72%
Glenn County3996.5%UnitedHealth Group, Inc. 43%
Del Norte County3004.4%Imperial Health Plan of California 37%
Colusa County2345.4%UnitedHealth Group, Inc. 63%
Mono County1738.8%Humana Inc. 38%
Modoc County1194.5%UnitedHealth Group, Inc. 44%
Sierra County11712.6%Humana Inc. 54%
Trinity County1123.0%UnitedHealth Group, Inc. 49%
Alpine County3713.0%Humana Inc. 100%