Free tool · public CMS data
Washington Medicare Advantage market share
In September 2026, 780,858 Washington Medicare beneficiaries were enrolled in a Medicare Advantage plan across 95 parent carriers and 39 counties, led by UnitedHealth Group, Inc. with 45.7% of counted enrollment.
Data month
September 2026
Advantage enrollees
780,858
+2.1% vs September 2025
Parent carriers
95
Advantage penetration
48.7%
CMS Medicare Monthly Enrollment, 2024
Carriers in Washington
CMS Monthly Enrollment by Contract/Plan/State/County (CPSC) · September 2026
| # | Parent organisation | Enrollees | Share | Counties | vs September 2025 |
|---|---|---|---|---|---|
| 1 | UnitedHealth Group, Inc. | 356,694 | 45.7% | 39 | +1.6% |
| 2 | Humana Inc. | 142,933 | 18.3% | 39 | +23.5% |
| 3 | Kaiser Foundation Health Plan, Inc. | 128,659 | 16.5% | 35 | -1.1% |
| 4 | CVS Health Corporation | 60,444 | 7.7% | 39 | -14.6% |
| 5 | Centene Corporation | 32,996 | 4.2% | 39 | -1.5% |
| 6 | Cambia Health Solutions, Inc. | 18,594 | 2.4% | 39 | -15.9% |
| 7 | Molina Healthcare, Inc. | 13,037 | 1.7% | 39 | -4.1% |
| 8 | Community Health Plan of Washington | 8,794 | 1.1% | 39 | -37.5% |
| 9 | Devoted Health, Inc. | 4,970 | 0.6% | 17 | +164.5% |
| 10 | Providence St Joseph Health | 4,353 | 0.6% | 18 | -10.7% |
| 11 | Elevance Health, Inc. | 3,909 | 0.5% | 39 | +5.0% |
| 12 | SCAN Group | 3,444 | 0.4% | 26 | — |
| 13 | Health Care Service Corporation | 857 | 0.1% | 39 | -17.6% |
| 14 | Blue Cross Blue Shield of Michigan Mutual Ins. Co. | 409 | 0.1% | 39 | -2.6% |
| 15 | California Physicians' Service | 350 | 0.0% | 39 | +1.2% |
| 16 | Highmark Health | 256 | 0.0% | 39 | -6.6% |
| 17 | Marquis Companies I, Inc. | 159 | 0.0% | 4 | — |
| 18 | Alameda Alliance for Health | 0 | 0.0% | 1 | — |
| 19 | Alignment Healthcare USA, LLC | 0 | 0.0% | 39 | — |
| 20 | AllCare Health, Inc. | 0 | 0.0% | 1 | — |
| 21 | Allina Health and Aetna Insurance Holding Company | 0 | 0.0% | 39 | — |
| 22 | AlohaCare | 0 | 0.0% | 2 | — |
| 23 | Astiva Health Holdings Incorporated | 0 | 0.0% | 3 | — |
| 24 | Athena Healthcare Holdings, LLC | 0 | 0.0% | 1 | — |
| 25 | ATRIO Health Plans | 0 | 0.0% | 6 | — |
| 26 | Aultman Health Foundation | 0 | 0.0% | 39 | — |
| 27 | Aware Integrated, Inc. | 0 | 0.0% | 39 | — |
| 28 | Banner Health | 0 | 0.0% | 1 | — |
| 29 | Baylor Scott & White Health | 0 | 0.0% | 1 | — |
| 30 | Baystate Health, Inc. | 0 | 0.0% | 39 | — |
| 31 | Blue Cross & Blue Shield of Rhode Island | 0 | 0.0% | 39 | — |
| 32 | Blue Cross and Blue Shield of Massachusetts, Inc. | 0 | 0.0% | 39 | — |
| 33 | Blue Cross Blue Shield of Arizona | 0 | 0.0% | 8 | — |
| 34 | Blue Cross Blue Shield of Kansas | 0 | 0.0% | 39 | — |
| 35 | Blue Cross Blue Shield of Nebraska | 0 | 0.0% | 39 | — |
| 36 | BlueCross BlueShield of Alabama | 0 | 0.0% | 39 | — |
| 37 | BlueCross BlueShield of South Carolina (BCBSSC) | 0 | 0.0% | 39 | — |
| 38 | BlueCross BlueShield of Tennessee | 0 | 0.0% | 39 | — |
| 39 | CAPITAL BLUE CROSS | 0 | 0.0% | 39 | — |
| 40 | CareFirst, Inc. | 0 | 0.0% | 39 | — |
| 41 | CareOregon, Inc. | 0 | 0.0% | 5 | — |
| 42 | CareSource | 0 | 0.0% | 4 | — |
| 43 | Champion Health Plans-USA, LLC. | 0 | 0.0% | 2 | — |
| 44 | Community Health Group | 0 | 0.0% | 2 | — |
| 45 | Corewell Health | 0 | 0.0% | 39 | — |
| 46 | CuraCor Solutions Corp. | 0 | 0.0% | 39 | — |
| 47 | EmblemHealth, Inc. | 0 | 0.0% | 39 | — |
| 48 | Fallon Community Health Plan, Inc. | 0 | 0.0% | 39 | — |
| 49 | Fenyx Health Holdings, Inc. | 0 | 0.0% | 39 | — |
| 50 | Gemstone Holdings, Inc. | 0 | 0.0% | 4 | — |
| 51 | General Catalyst Group Management Holdings LP | 0 | 0.0% | 39 | — |
| 52 | Gold Kidney Health Plan | 0 | 0.0% | 1 | — |
| 53 | Guidewell Mutual Holding Corporation | 0 | 0.0% | 39 | — |
| 54 | Hawaii Medical Service Association | 0 | 0.0% | 39 | — |
| 55 | Health Plan of San Mateo | 0 | 0.0% | 1 | — |
| 56 | Healthfirst, Inc. | 0 | 0.0% | 39 | — |
| 57 | HealthPartners, Inc. | 0 | 0.0% | 39 | — |
| 58 | Henry Ford Health System | 0 | 0.0% | 39 | — |
| 59 | Horizon Mutual Holdings, Inc | 0 | 0.0% | 39 | — |
| 60 | Imperial Health Plan of California | 0 | 0.0% | 13 | — |
| 61 | Independence Health Group, Inc. | 0 | 0.0% | 39 | — |
| 62 | Independent Health Association, Inc. | 0 | 0.0% | 39 | — |
| 63 | INLAND EMPIRE HEALTH PLAN | 0 | 0.0% | 1 | — |
| 64 | Intermountain Health Care, Inc. | 0 | 0.0% | 7 | — |
| 65 | Lifetime Healthcare, Inc. | 0 | 0.0% | 39 | — |
| 66 | Local Initiative Health Authority for LA County | 0 | 0.0% | 2 | — |
| 67 | Louisiana Health Service & Indemnity Company | 0 | 0.0% | 39 | — |
| 68 | Lumeris Group Holdings Corporation | 0 | 0.0% | 2 | — |
| 69 | Martin's Point Health Care, Inc. | 0 | 0.0% | 39 | — |
| 70 | Medica Holding Company | 0 | 0.0% | 39 | — |
| 71 | MEDICAL MUTUAL OF OHIO | 0 | 0.0% | 39 | — |
| 72 | Memorial Hermann Health System | 0 | 0.0% | 1 | — |
| 73 | Mercy Care | 0 | 0.0% | 4 | — |
| 74 | MHH Healthcare, L.P. | 0 | 0.0% | 1 | — |
| 75 | MVP Health Care, Inc. | 0 | 0.0% | 39 | — |
| 76 | Network Health, Inc. | 0 | 0.0% | 39 | — |
| 77 | Orange County Health Authority | 0 | 0.0% | 1 | — |
| 78 | PacificSource | 0 | 0.0% | 14 | -100.0% |
| 79 | Point32Health, Inc. | 0 | 0.0% | 4 | — |
| 80 | Samaritan Health Services, Inc. | 0 | 0.0% | 1 | — |
| 81 | Sanford Health | 0 | 0.0% | 1 | — |
| 82 | SANTA CLARA COUNTY HEALTH AUTHORITY | 0 | 0.0% | 4 | — |
| 83 | Sharp Healthcare | 0 | 0.0% | 1 | — |
| 84 | St Francis Health System & St John Health System | 0 | 0.0% | 1 | — |
| 85 | The Health Plan of West Virginia, Inc. | 0 | 0.0% | 39 | — |
| 86 | The Regents of the University of California | 0 | 0.0% | 2 | — |
| 87 | Thomas Jefferson University | 0 | 0.0% | 1 | — |
| 88 | Trinity Health Corporation | 0 | 0.0% | 11 | — |
| 89 | Ultimate Healthcare Holdings, LLC | 0 | 0.0% | 2 | — |
| 90 | UNICO Services, Inc. | 0 | 0.0% | 1 | — |
| 91 | Universal Health Services, Inc. | 0 | 0.0% | 10 | — |
| 92 | University of Wisconsin Hospitals and Clincs Autho | 0 | 0.0% | 1 | — |
| 93 | UPMC Health System | 0 | 0.0% | 39 | — |
| 94 | USAble Mutual Insurance Company | 0 | 0.0% | 39 | — |
| 95 | Visiting Nurse Service of New York | 0 | 0.0% | 1 | — |
County view
Leading carrier and Advantage enrollment in each Washington county. Penetration is from CMS Medicare Monthly Enrollment, 2024.
| County | Advantage enrollees | Leading carrier | Leader share | Carriers | Penetration |
|---|---|---|---|---|---|
| King | 196,753 | UnitedHealth Group, Inc. | 44.2% | 75 | 53.5% |
| Pierce | 91,203 | UnitedHealth Group, Inc. | 55.4% | 67 | 50.1% |
| Snohomish | 91,170 | UnitedHealth Group, Inc. | 53.6% | 65 | 58.9% |
| Clark | 73,291 | Kaiser Foundation Health Plan, Inc. | 30.0% | 70 | 66.7% |
| Spokane | 70,645 | UnitedHealth Group, Inc. | 60.4% | 59 | 55.8% |
| Thurston | 36,958 | UnitedHealth Group, Inc. | 45.0% | 58 | 51.5% |
| Kitsap | 26,791 | UnitedHealth Group, Inc. | 32.7% | 61 | 39.4% |
| Whatcom | 25,181 | UnitedHealth Group, Inc. | 37.4% | 57 | 49.4% |
| Yakima | 21,671 | UnitedHealth Group, Inc. | 59.1% | 57 | 44.3% |
| Cowlitz | 19,531 | Kaiser Foundation Health Plan, Inc. | 38.7% | 55 | 65.7% |
| Skagit | 16,003 | UnitedHealth Group, Inc. | 51.5% | 56 | 45.0% |
| Benton | 13,500 | UnitedHealth Group, Inc. | 52.8% | 57 | 28.6% |
| Lewis | 12,996 | UnitedHealth Group, Inc. | 76.6% | 58 | 54.6% |
| Island | 11,177 | UnitedHealth Group, Inc. | 60.7% | 58 | 41.5% |
| Mason | 8,854 | UnitedHealth Group, Inc. | 46.7% | 52 | 42.7% |
| Chelan | 8,002 | Centene Corporation | 52.7% | 53 | 38.6% |
| Clallam | 6,774 | UnitedHealth Group, Inc. | 77.2% | 58 | 22.9% |
| Grant | 6,665 | Humana Inc. | 41.9% | 55 | 33.6% |
| Grays Harbor | 5,145 | Centene Corporation | 52.0% | 57 | 24.2% |
| Stevens | 5,019 | Humana Inc. | 73.8% | 55 | 36.7% |
| Walla Walla | 4,856 | UnitedHealth Group, Inc. | 45.3% | 52 | 31.0% |
| Franklin | 4,654 | UnitedHealth Group, Inc. | 55.6% | 54 | 32.3% |
| Douglas | 3,773 | Centene Corporation | 50.4% | 53 | 37.9% |
| Okanogan | 3,433 | Centene Corporation | 40.1% | 51 | 26.1% |
| Kittitas | 2,768 | Humana Inc. | 54.5% | 54 | 26.4% |
| Jefferson | 2,469 | UnitedHealth Group, Inc. | 42.3% | 53 | 17.6% |
| Whitman | 1,905 | UnitedHealth Group, Inc. | 51.5% | 53 | 23.3% |
| Asotin | 1,736 | Centene Corporation | 64.4% | 51 | 29.8% |
| Pacific | 1,639 | UnitedHealth Group, Inc. | 38.6% | 53 | 18.5% |
| Pend Oreille | 1,221 | Centene Corporation | 37.6% | 53 | 25.7% |
| San Juan | 989 | Centene Corporation | 36.5% | 54 | 23.3% |
| Adams | 895 | Centene Corporation | 44.7% | 50 | 33.7% |
| Wahkiakum | 646 | Kaiser Foundation Health Plan, Inc. | 54.3% | 54 | 43.7% |
| Skamania | 608 | Devoted Health, Inc. | 29.1% | 54 | 19.9% |
| Klickitat | 597 | Humana Inc. | 48.6% | 54 | 10.4% |
| Ferry | 568 | Centene Corporation | 65.5% | 51 | 21.8% |
| Lincoln | 550 | Humana Inc. | 51.8% | 53 | 22.4% |
| Columbia | 200 | Centene Corporation | 38.0% | 50 | 21.5% |
| Garfield | 22 | Centene Corporation | 100.0% | 50 | 11.8% |
What is missing
CMS suppresses any plan-county cell with fewer than 11 enrollees. Those enrollees are missing from these counts, so every figure is a floor, not an exact total.
What is counted
Counts cover Medicare Advantage contracts only (Local CCP, Regional CCP, PFFS and MSA). Standalone Part D drug plans, cost plans, HCPP and PACE contracts are excluded.
Source: CMS Monthly Enrollment by Contract/Plan/State/County (CPSC).