Agricultural Real Property Assessments
Permanent plantings such as vineyards or orchards are assessable as Real Property under Proposition 13 along with any fixture that supports the improvement such as drip, trellis, stakes, etc. Newly planted vineyards will be exempt from taxation for the first 3 years and new orchards will be exempt for 4 years. After the exemption period, the growing improvement will be assessed at market value and increase no more than 2% under Prop 13. Grafting a vine or tree is considered a new planting and will reset the exemption period.
Ag Decline in Value
Under Proposition 13, a property’s assessment is determined by its factored base‑year value. Proposition 8 allows for a temporary reduction when a property’s current market value falls below that Proposition 13 value. If you believe that you could not sell your property for the total assessed value as of 1/1/2026, please reach out to the Clerk of the Board before November 30th to file an assessment appeal.
A Prop 8, or temporary decline in value, reduction will need to be supported by comparables sales. Please review sales of similar properties around January 2026 to determine the market value range and how that compares to the total assessed value of your property. Seeking the assistance of a real estate professional or fee appraisals completed around January 2026 could be beneficial in determining an opinion of market value.
Williamson Act
For land enrolled in the Williamson Act, assessments are based on a restricted income‑based valuation rather than full market value, which can result in lower assessed values for agricultural properties. Properties that are assessed under Williamson Act have had an additional risk component added to the restricted income approach to address the uncertainty and decline in grape income which has resulted in lower 2026 assessment for most properties.
Vineyard Removal
Any vines that are removed during the 2026 calendar year, will be reported to the Assessor in early 2027 via Online Ag Reporting or by contacting our office for a paper filing and will be reflected on next year’s annual bill.
Abandoned vineyards that are still in the ground will remain assessable until removed.
Informal 2027 Prop 8 Reviews
The informal Prop 8 review period for 1/1/2027 will be open December- March 15th. Any property owner who believes their current market value is below either their Proposition 13 assessed value or their Williamson Act restricted value are encouraged to file an informal review when the form is available.
Planting Records
The Sonoma County Assessor’s Office strives to annually review plantings on vineyard/orchard properties. The online portal file is now closed. Please contact our office at 707-565-1888 or 1-800-244-1034 to discuss your reporting options.
Williamson Act Assessment
Agricultural land and growing assessments on parcels under a Williamson Act contract receive a restricted assessment. A restricted assessment is an annual restricted income approach for Ag land and growing while residences, other structural improvements, land supporting residential uses and growing fixtures are assessed under Prop 13 to create a blended total assessment.
*Please note that this is not a representation of an actual valuation and is only for demonstration purposes.
Supplemental Assessments for Real Property Fixed Equipment
Starting in the 2025/2026 tax year, the Assessor’s office will be issuing supplemental assessments for changes in fixed equipment that support vineyards and orchards as recommended by the State Board of Equalization. Changes in equipment such as drip, trellis, stakes, etc. will now be captured as a supplemental assessment as of 12/30. These changes will be reported online annually via the Annual Planting Record during the filing period. Our staff has diligently processed the backlog of unworked Planting Records and notices of change will be going out as we approach the closing of the 2025 tax roll. Please contact our office if you have questions.
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