Sonoma County assessor reports $127 billion roll; Rohnert Park among cities with highest growth

D.Aie Proto, Sonoma County Clerk, Recorder and Assessor, told the Rohnert Park City Council on July 22 that the county closed the 2025—1026 assessment roll at just over $127 billion in total assessed value.

Proto said about $123 billion of the roll is secured property and roughly $4 million is unsecured, and that the countywide total represents a 5.44% increase from the prior year. She explained assessments are set as of Jan. 1 and reassessed on property transfers or new construction, consistent with state law and Proposition 13.

Rian Jagger, chief deputy assessor, joined Proto and said land and improvements accounted for the largest share of growth. Proto noted that some incorporated and unincorporated areas saw larger increases; she identified Rohnert Park as among the cities with higher growth due to recent building activity and transfers.

The presenters reviewed how the office handles roll corrections and supplemental assessments (for example when a property sells) and reminded the council that tax bills are prepared by the auditor-controller, treasurer-tax collector and are still based on the Jan. 1 lien date.

Council members asked for clarifications on the city comparison slides and growth figures; officials reiterated that assessments rise annually by the CPI or 2%, whichever is less, and that Proposition 19 allows certain base-year-value transfers for qualifying homeowners over 55. Contact information for the assessorwas provided on screen at the end of the presentation.

Why it matters: Assessment-roll totals determine property-tax allocations and underpin parts of the city budget. Rohnert Parkresidents and officials will see these valuation changes reflected in future revenue expectations and in supplemental assessments when properties transfer.