Medicare Advantage in Marin County, CA, for 2027.
CMS lists 23 Medicare Advantage plans here for 2027, the same as 2026. 29,293 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 71 with 10 or fewer members here. CMS moves 0 members to another plan, and 20,685 stay in the same plan.
| Plan | Insurer | Members | Why |
|---|---|---|---|
| Alignment Health Honor+ Plan (HMO) | Alignment Healthcare USA | 57 | Plan leaves this county |
| Kaiser Permanente Sr Adv Enhanced Sac., Sonoma (HMO) | Kaiser Foundation Health Plan | 45 | Plan leaves this county |
| Kaiser Permanente Sr Advantage Basic Sac., Sonoma (HMO) | Kaiser Foundation Health Plan | 37 | Plan leaves this county |
| Kaiser Permanente Senior Advantage Alam., SF, Napa (HMO) | Kaiser Foundation Health Plan | 19 | Plan leaves this county |
| Kaiser Permanente Sr Adv Enhanced Contra Costa (HMO) | Kaiser Foundation Health Plan | 11 | Plan leaves this county |
Who holds the members
- Kaiser Foundation Health Plan23,789
- Alignment Healthcare USA1,827
- California Physicians' Service1,171
- UnitedHealth1,080
- Humana520
- Elevance Health451
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 Senior Advantage Basic Marin (HMO)Kaiser Foundation Health Plan4.5
- Kaiser Permanente Sr Adv Enhanced Marin San Mateo (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 23 plans, open each plan's benefits and star measures, and see what each insurer paid agents in 2026.
Open Marin 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.