Medicare Advantage in Sonoma County, CA, for 2027.
CMS lists 13 Medicare Advantage plans here for 2027, 4 more than 2026 (9). 65,790 people in the county had an individual Medicare Advantage plan in October 2026.
Sources: CMS CY2027 plan file (October 2026 release), CMS CY2026 plan file (September 2026 release), CMS enrollment by county (CPSC), October 2026, CMS 2027 Plan Crosswalk (October 1, 2026), CMS 2027 Star Ratings Data Tables (October 8, 2026). Member counts are floors because CMS hides counts of 10 or fewer.
The county in numbers
Plans that end here for 2027
5 plans with members in the county end or leave it, plus 94 with 10 or fewer members here. CMS moves 0 members to another plan, and 46,753 stay in the same plan.
| Plan | Insurer | Members | Why |
|---|---|---|---|
| Anthem Dual Advantage 2 (PPO D-SNP) | Elevance Health | 852 | Plan terminated |
| Alignment Health My Choice (PPO) | Alignment Healthcare USA | 634 | Plan terminated |
| Kaiser Permanente Sr Adv Enhanced Marin San Mateo (HMO) | Kaiser Foundation Health Plan | 35 | Plan leaves this county |
| Kaiser Permanente Senior Advantage Alam., SF, Napa (HMO) | Kaiser Foundation Health Plan | 29 | Plan leaves this county |
| CareAdvantage (HMO D-SNP) | Health Plan of San Mateo | 11 | Plan leaves this county |
Who holds the members
- Kaiser Foundation Health Plan51,927
- Imperial Health Plan of California4,954
- Alignment Healthcare USA3,624
- UnitedHealth1,858
- Elevance Health1,686
- California Physicians' Service1,227
Individual Medicare Advantage members by parent company, October 2026.
Top rated plans sold here
- Kaiser Permanente Dual Complete North P25 (HMO D-SNP)Kaiser Foundation Health Plan4.5
- Kaiser Permanente Sr Adv Enhanced Sac., Sonoma (HMO)Kaiser Foundation Health Plan4.5
- Kaiser Permanente Sr Advantage Basic Sac., Sonoma (HMO)Kaiser Foundation Health Plan4.5
2027 overall Star Rating, 4.5 or more. Each plan's measure stars are in the county lookup.
See every plan, premium and copay in the free lookup.
Sort all 13 plans, open each plan's benefits and star measures, and see what each insurer paid agents in 2026.
Open Sonoma in the lookupWorking this county for AEP?
The AEP 2027 County Kit puts this county and your others in one file: the plans that end, where members land, what is still sold and a crosswalk sheet, with every number tied to its CMS file.
See the AEP 2027 County KitAll California county pages. Facts from public CMS files, prepared by Health and Tech Now. Not plan advice. Check a plan's Summary of Benefits before you enroll.