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Medicare Advantage Enrollment Tracker · California

Medicare Advantage Enrollment in California

California had 3,750,935 Medicare Advantage members in September 2026, by the CMS county file, which includes employer group plans. That is up 2.2% from Sep 2025, close to the national 2.0%. California ranks 1st by members and holds 10.5% of the national total.

Kaiser leads with 41.5% of members who have a carrier label (contract file, September 2026). Among individual plans, which leave out employer group coverage, enrollment is up 2.7% in the 12 months to September 2026.

By Senior Deal Club Standards Desk · Data as of September 2026 · Editorial policy

Data as ofCMS public files, monthly snapshot

  • These totals include employer and union group plans.
    Why this matters

    The CMS contract and county files count group plans that retirees get through a former employer. They are not plans you can pick on your own. Counts here are larger than the individual-plan counts on county pages.

  • Some months are missing from the source.
    Why this matters

    CMS did not publish every month. Lines break at a missing month instead of guessing a value. A dotted line, where shown, only joins the two sides.

California at a glance

Medicare Advantage members

3,750,935

California members by month: from 3.21M in Jan 2023 to 3.75M in Sep 2026

County file · Sep 2026. Includes employer group plans. Rank: 1.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.

12-month change

+2.2%

up 2.2 percent vs Sep 2025

County file · Sep 2026. National: +2.0%.

Share of national total

10.5%

County file · Sep 2026. Of jurisdictions that report every month.

Individual plan members

2,981,829

Individual MA · Sep 2026. Employer group plans left out.

Individual MA · Sep 2026
Individual Medicare Advantage plans (IND), from county data. Employer and union group plans are left out, so counts are smaller than in the other two files.

Largest carrier

Kaiser

41.5% of members with a carrier label. Contract file · Sep 2026.

California members by month

Medicare Advantage members in California

Members, by month.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.
Medicare Advantage members in CaliforniaLine chart, January 2023 to September 2026. California: 3.75M in September 2026. Shaded bands mark months with no data.3.2M3.4M3.6M3.8M2023202420252026California3.75M
Medicare Advantage members in CaliforniaLine chart, January 2023 to September 2026. California: 3.75M in September 2026. Shaded bands mark months with no data.3.2M3.4M3.6M3.8M20232025California3.75M
  • California
  • Shaded: no data that month
View the data table
Medicare Advantage members in California: values by month
MonthCalifornia
Sep 20263.75M
Aug 20263.75M
Jul 20263.74M
Jun 20263.73M
May 20263.72M
Apr 20263.71M
Mar 20263.7M
Feb 20263.69M
Jan 20263.66M
Dec 20253.69M
Nov 20253.69M
Oct 20253.68M
Sep 20253.67M
Aug 20253.66M
Jul 20253.65M
Jun 20253.64M
May 20253.63M
Apr 20253.62M
Mar 20253.61M
Feb 20253.59M
Jan 20253.56M
Dec 20243.57M
Nov 20243.56M
Oct 20243.56M
Sep 20243.55M
Aug 20243.54M
Jul 20243.53M
Jun 20243.52M
May 20243.52M
Apr 20243.5M
Mar 20243.49M
Feb 20243.46M
Jan 20243.44M
Dec 2023–
Nov 20233.42M
Oct 20233.41M
Sep 20233.4M
Aug 20233.39M
Jul 2023–
Jun 20233.37M
May 20233.36M
Apr 20233.35M
Mar 20233.34M
Feb 20233.27M
Jan 20233.21M

County file · Sep 2026. Employer group plans included.

California and the nation, Jan 2023 = 100

Each line is members divided by members in the start month, times 100.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.
California and the nation, Jan 2023 = 100Line chart, January 2023 to September 2026. California: 117 in September 2026. National (same jurisdictions each month): 117.8 in September 2026. Shaded bands mark months with no data.1001051101151202023202420252026National117.8California117
California and the nation, Jan 2023 = 100Line chart, January 2023 to September 2026. California: 117 in September 2026. National (same jurisdictions each month): 117.8 in September 2026. Shaded bands mark months with no data.10010511011512020232025National117.8California117
  • California
  • National (same jurisdictions each month)
  • Shaded: no data that month
View the data table
California and the nation, Jan 2023 = 100: values by month
MonthCaliforniaNational (same jurisdictions each month)
Sep 2026117117.8
Aug 2026116.8117.8
Jul 2026116.5117.5
Jun 2026116.3117.4
May 2026116117.2
Apr 2026115.7116.9
Mar 2026115.4116.7
Feb 2026115.1116.3
Jan 2026114.1114.7
Dec 2025115.1115.9
Nov 2025115115.9
Oct 2025114.8115.7
Sep 2025114.5115.5
Aug 2025114.3115.3
Jul 2025113.9115
Jun 2025113.7114.8
May 2025113.3114.4
Apr 2025113114.2
Mar 2025112.7113.8
Feb 2025112.1113.4
Jan 2025110.9111.9
Dec 2024111.2112
Nov 2024111.2112
Oct 2024111111.7
Sep 2024110.7111.5
Aug 2024110.4111.2
Jul 2024110.1110.9
Jun 2024109.9110.7
May 2024109.9110.5
Apr 2024109.3110
Mar 2024108.8109.7
Feb 2024108109.3
Jan 2024107.3108.7
Dec 2023––
Nov 2023106.8105.9
Oct 2023106.4105.6
Sep 2023106.2105.2
Aug 2023105.9104.9
Jul 2023––
Jun 2023105104.1
May 2023104.8103.8
Apr 2023104.5103.4
Mar 2023104.2103
Feb 2023102102.2
Jan 2023100100

County file · Sep 2026. National line sums the jurisdictions that report in every month.

Individual plans

Individual plans leave out employer and union group coverage, so counts are smaller than in the county file.

Carrier share in California

Share of members whose contract has a carrier label, September 2026 against September 2025.

Contract file · Sep 2026
CMS contract file (SCC). All Medicare Advantage contracts, with employer and union group plans included. It still lists Connecticut and Alaska.

Kaiser leads with 41.5% of members who have a carrier label (contract file, September 2026).

SCAN gained 3.4 points in 12 months; most of that change came in January 2026.

UnitedHealthcare lost 3.0 points in 12 months; most of that change came in January 2026.

UnitedHealthcare and Humana together hold 14.4%, down 2.9 points from Sep 2025.

The market is about as concentrated as a year earlier (direction only; the level depends on how carriers are grouped).

Carrier share, Sep 2025 to Sep 2026

Percent of members with a carrier label. Largest carriers.

Carrier share, Sep 2025 to Sep 2026Slope chart comparing Sep 2025 with Sep 2026. Kaiser: 40.9% to 41.5%; SCAN: 8.4% to 11.8%; UnitedHealthcare: 13.4% to 10.4%; Elevance/Anthem: 8.8% to 7.7%; Alignment Health: 5.3% to 6.4%; Humana: 3.8% to 4.0%.Sep 2025Sep 2026Kaiser 40.9%41.5% KaiserSCAN 8.4%11.8% SCANUnitedHealthcare 13.4%10.4% UnitedHealthcareElevance/Anthem 8.8%7.7% Elevance/AnthemAlignment Health 5.3%6.4% Alignment HealthHumana 3.8%4.0% Humana
Carrier share, Sep 2025 to Sep 2026Slope chart comparing Sep 2025 with Sep 2026. Kaiser: 40.9% to 41.5%; SCAN: 8.4% to 11.8%; UnitedHealthcare: 13.4% to 10.4%; Elevance/Anthem: 8.8% to 7.7%; Alignment Health: 5.3% to 6.4%; Humana: 3.8% to 4.0%.Sep 2025Sep 2026Kaiser 40.9%41.5%SCAN 8.4%11.8%UHC 13.4%10.4%Elevance 8.8%7.7%Alignment 5.3%6.4%Humana 3.8%4.0%
View the data table
Carrier share, Sep 2025 to Sep 2026: Sep 2025 and Sep 2026
NameSep 2025Sep 2026Change
Kaiser40.9%41.5%+0.6 pts
SCAN8.4%11.8%+3.4 pts
UnitedHealthcare13.4%10.4%−3.0 pts
Elevance/Anthem8.8%7.7%−1.1 pts
Alignment Health5.3%6.4%+1.1 pts
Humana3.8%4.0%+0.2 pts

Contract file · Sep 2026. Employer group plans included.

Carrier share of Medicare Advantage members with a carrier label, California, September 2026
CarrierShare, Sep 2026Share, Sep 2025ChangeMembers
Kaiser41.5%40.9%+0.6 pts1,528,010
SCAN11.8%8.4%+3.4 pts433,615
UnitedHealthcare10.4%13.4%−3.0 pts381,652
Elevance/Anthem7.7%8.8%−1.1 pts283,036
Alignment Health6.4%5.3%+1.1 pts236,691
All other carriers4.1%––149,897
Humana4.0%3.8%+0.2 pts146,747
Aetna/CVS2.7%3.6%−0.9 pts100,168
Centene/Wellcare2.2%3.1%−0.9 pts82,234
Blue Shield of California2.1%2.5%−0.4 pts77,304
Molina1.7%3.0%−1.3 pts63,359
Astiva Health Holdings Incorporated1.4%1.0%+0.4 pts53,192
Imperial Health Plan of California1.4%0.7%+0.8 pts52,798
Clever Care Health Plan1.4%0.8%+0.6 pts52,613
INLAND EMPIRE HEALTH PLAN1.0%1.1%0.0 pts38,297

Insurer not assigned in CMS data: 1.8% of all members in Sep 2026, 1.9% in Sep 2025. Shares leave these members out. Contract IDs are renumbered each January, so this page follows carriers, not contracts. A contract that serves several states carries one carrier label, so a carrier can appear in a state where it is not a local plan. See the carrier view for the whole nation.

Biggest counties in California

Individual plan members and the 12-month change for each county, from county data.

Individual MA · Sep 2026
Individual Medicare Advantage plans (IND), from county data. Employer and union group plans are left out, so counts are smaller than in the other two files.
Biggest counties in California by individual Medicare Advantage members, September 2026
CountyMembers12-month changeLeading carrierLeader's share
Los Angeles817,043+3.2%Kaiser29.8%
Orange296,250+3.2%SCAN28.8%
San Diego284,862+2.5%Kaiser29.5%
Riverside248,115+2.5%Kaiser26.3%
San Bernardino203,033+2.9%Kaiser28.5%
Santa Clara129,894+3.9%Kaiser50.8%
Sacramento122,357+5.2%Kaiser54.1%
Alameda104,559+4.8%Kaiser72.7%
Contra Costa78,389+0.9%Kaiser79.0%
Fresno64,716+2.8%Alignment Health29.8%

1 of 58 counties have no individual plan row. Those read "not reported", not zero. Browse all counties.

Common questions

How many people have Medicare Advantage in California?

California had 3,750,935 members in September 2026, by the CMS county file (employer group plans included). Individual plans, which leave out employer group coverage, had 2,981,829 members in September 2026.

Is Medicare Advantage growing in California?

Enrollment is up 2.2% from Sep 2025 to Sep 2026, close to the national 2.0%. Among individual plans, which leave out employer group coverage, enrollment is up 2.7% in the 12 months to September 2026.

Which carrier has the most Medicare Advantage members in California?

Kaiser leads with 41.5% of members who have a carrier label (contract file, September 2026). UnitedHealthcare and Humana together hold 14.4%, down 2.9 points from Sep 2025. Shares leave out members whose contract has no carrier label: 1.8% of members.

Cite and download

Cite this page

Senior Deal Club Standards Desk. Medicare Advantage Enrollment in California, data as of September 2026. Source: CMS public enrollment files. https://www.seniordealclub.com/medicare-advantage/enrollment/states/california

Download California CSV

Data: CMS public enrollment files, in a monthly snapshot processed by TapQuality. Senior Deal Club is not affiliated with Medicare or any government agency.

These pages are educational. They are not plan advice. How the numbers are built · Editorial policy