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Medicare Advantage plan exits 2027 in Sonoma County, CA
1,496 of the 48,067 Medicare Advantage members in Sonoma County (3.1%) are in a plan that is not sold in the county for 2027: 2 of the 9 plans sold there in September 2026 end, from the CMS 2027 Landscape and crosswalk. California: 5.5%; the nation: 10.6%.
Period: plan year 2027 against September 2026 members · Updated 2026-10-20 · Next: CMS January 2027 enrollment (February 2027): where the members landed
- members, Sept 2026
- 48,067
- members, Sept 2026
- must pick for 2027
- 1,496
- must pick for 2027
- share of members
- 3.1%
- share of members
- plans end
- 2 of 9
- plans end
Medicare Advantage members in Sonoma County, 2015 to 2026
MA enrollment in September each year, with MA penetration (members over Medicare eligibles) at the top of each bar, from the CMS state-county penetration file. Navy: the last two years. 13 plans are listed for the county for 2027 against 9 for 2026.
The plans that end for 2027
Every plan sold in Sonoma County in September 2026 with members whose plan is not sold there for 2027: how it went (terminated, or its service area reduced so it continues elsewhere), the members the same company offers a new or renumbered plan of the same type, and the members whose company sells nothing in the county next year.
| Plan | Company | Type | Members | Terminated | Service area reduced | Offered a new or renumbered plan | Company gone |
|---|---|---|---|---|---|---|---|
| Anthem Dual Advantage 2 (PPO D-SNP) H4704-002 | Elevance Health, Inc. | D-SNP PPO | 860 | 860 | 0 | 0 | 0 |
| Alignment Health My Choice (PPO) H4961-003 | Alignment Healthcare USA, LLC | Regular PPO | 636 | 636 | 0 | 0 | 0 |
| 2 plans | 1,496 | 1,496 | 0 | 0 | 0 |
Download this table (CSV, CC BY 4.0) · cells under 11 members are suppressed by CMS and count as zero, so every count is a floor.
By company in Sonoma County
| Company | Members, Sept 2026 | Plans | Plans ending | Must pick | Share of own members | Offered a new or renumbered plan | Company gone |
|---|---|---|---|---|---|---|---|
| Elevance Health, Inc. | 860 | 1 | 1 | 860 | 100.0% | 0 | 0 |
| Alignment Healthcare USA, LLC | 3,608 | 2 | 1 | 636 | 17.6% | 0 | 0 |
| Kaiser Foundation Health Plan, Inc. | 38,669 | 3 | 0 | 0 | 0.0% | 0 | 0 |
| Imperial Health Plan of California | 4,930 | 3 | 0 | 0 | 0.0% | 0 | 0 |
Sonoma County against California and the nation
| Measure | County | California | United States |
|---|---|---|---|
| Must pick for 2027, share of members | 3.1% | 5.5% | 10.6% |
| Must pick for 2026 | 15.8% | 10.1% | |
| Must pick for 2025, members | 3,259 of 46,816 | ||
| Must pick for 2026, members | 7,580 of 47,929 | ||
| Must pick for 2027, members | 1,496 of 48,067 |
State and national figures: the California hub and the national report.
Star Ratings 2027 in Sonoma County
| Measure | 2027 | 2026 | Change |
|---|---|---|---|
| Members in contracts rated 4+ stars | 93.4% | 95.4% | -2.0 pts |
| Member-weighted average star | 4.38 | 4.36 | +0.02 |
| Rated contracts with members here | 16 | 17 |
Members by star, 2027: 4.5: 55,487 · 4.0: 4,997 · 3.5: 2,994 · 3.0: 41 · 2.5: 1,219; 860 in unrated contracts. Each contract's 2027 overall star (CMS, released 2026-10-08) weighted by its 2026-09 members in the county, individual and group; 2026 by 2025-09 members.
Sources
- CMS Medicare Advantage/Part D Landscape, plan year 2027: landscape_cy2027-landscape-202609-1.zip (CMS, September 2026); CMS plan crosswalk CY2027.
- CMS monthly enrollment by contract, plan and county, 2026-09 (and the two Septembers before, for the series).
- CMS MA state-county penetration file, September of each year (eligibles, enrollment, penetration).
- CMS Star Ratings 2027, released 2026-10-08. Page object written 2026-10-20.
Receipts: athena(table=medicare_semantic.exits_cells_county_2027_v1, block=plans) 042eb472aa7d…; athena(table=medicare_semantic.exits_cells_county_2025_v1, medicare_semantic.exits_cells_county_2026_v1, medicare_semantic.exits_cells_county_2027_v1, block=series) ee9fd56a8632…; athena(table=medicare_semantic.ma_spine_county_market_v20261012b, block=market) e6c1b5ce62c0…; athena(table=medicare_semantic.ma_spine_contract_stars_v20261012b, weights=medicare_semantic.ma_spine_enroll_plan_county_v20261012a, block=stars) c39711c388e0…. Suppressed cells count as zero in every count.
Cite: Vlada Health (2026). Medicare Advantage plan exits 2027 in Sonoma County, CA. https://www.vladahealth.com/medicare-advantage/ca/sonoma. Data: CC BY 4.0.
Method
- Population: members of individual Medicare Advantage plans (H and R contracts, plans 001 to 799, special needs plans included; employer group, Cost, MMP and PACE excluded) in the county in September 2026.
- Must pick: the CMS crosswalk names no successor plan sold in the county for 2027; members CMS moves to a successor in the county are not counted.
- Terminated: the plan is gone from every county. Service area reduced: the plan continues elsewhere but not here. Offered a new or renumbered plan: the same company sells, in this county, the same name under a new number or a new plan of the same HMO or PPO and special needs type. Company gone: no plan of any type from that company in the county.
- Stars: each contract's overall star weighted by its September members in the county; unrated contracts counted apart, never as zero stars. Penetration: the CMS file's own eligibles and MA enrollment.
- Suppression: CMS hides cells under 11 members; they count as zero, so every count is a floor and every share is not.
The full method and the national tables: How we counted, and how to check it.
Questions
- How many Medicare Advantage members in Sonoma County must pick a new plan for 2027?
- 1,496 of 48,067 members (3.1%): their plan is not sold in the county for 2027 according to the CMS crosswalk and Landscape. California as a whole: 5.5%; the nation: 10.6%.
- Which plan in Sonoma County ends with the most members?
- Anthem Dual Advantage 2 (PPO D-SNP) (H4704-002, Elevance Health, Inc.): 860 members in September 2026, terminated.
- Which company ended the most plans in Sonoma County for 2027?
- Elevance Health, Inc.: 860 of its 860 members in the county (100.0%), 1 of its 1 plans.
- What share of Sonoma County's Medicare eligibles are in Medicare Advantage?
- 53.6% in September 2026: 66,059 of 123,166 eligibles, from the CMS state-county penetration file.
- How are Sonoma County's members rated for 2027?
- 93.4% of members are in contracts rated 4 stars or more for 2027 (95.4% the year before); the member-weighted average star is 4.38 over 16 rated contracts.
- How does 2027 compare with 2026 in Sonoma County?
- 7,580 members (15.8%) had to pick a new plan for 2026; for 2027 it is 1,496 (3.1%), a change of -6,084 members.
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Use Vlada. In Sonoma County, California, which Medicare Advantage plans are not sold for 2027, how many members are in each, and what did 2026 look like? Give me a table with the source file, the data vintage and the response hash.
Behind it: get_county_view (state CA, county Sonoma) and get_landscape_exits (group_by county).