Property Tax Appeals in Napa County, California
Napa County's Clerk of the Board states that a complete Assessment Appeal Application requires the applicable non-refundable processing fee: $75 for residential properties and $150 for commercial or business properties, under fees revised as of January 6, 2025, and that multiple appeals for the same parcel each require a separate application and fee. The page states applications are filed with the Clerk of the Board and directs applicants to the Assessment Appeal Application form; it does not describe an online e-filing portal. Regular Assessments must be filed between July 2 and November 30 of the current year. FairPath can help an owner organize a comparison table, condition photos, official links, and a filing checklist. It does not file the application, choose the owner's opinion of value, pay the fee, or communicate with the Assessor's Office on the owner's behalf.
Assessment context: Begin with the Assessor's parcel record and confirm whether the dispute concerns the January 1, 2026 lien-date value on the regular roll, a supplemental assessment tied to a change of ownership or new construction, or a roll change, escape, or calamity reassessment. Napa County sits in California's North Coast wine country north of San Francisco Bay, where much of the valley floor is protected agricultural-preserve land planted in vineyards between the Mayacamas Mountains to the west and the Vaca Mountains to the east. The county also includes the city of Napa and smaller towns such as St. Helena, Calistoga, and Yountville, along with hillside and rural wildland parcels. A property a few miles away may sit in a different agricultural-preserve or hillside zoning designation, so land use, vineyard designation, and site access should be confirmed against the Assessor's record rather than assumed from a map.
Filing process: Napa County's Clerk of the Board directs applicants to the Assessment Appeal Application, available from the Assessment Appeals Documents page, and states that a complete application with all applicable information and the required non-refundable processing fee — $75 for residential properties or $150 for commercial and business properties — must be submitted to the Clerk of the Board. Regular Assessments must be filed between July 2 and November 30 of the current year; assessments outside that window run on a 60-day or, for calamity reassessments, 180-day clock from the date on the relevant notice or its postmark, whichever is later. The Clerk of the Board's page states that failure to meet the filing criteria will result in rejection of the application, and that property taxes remain due while an appeal is pending.
Evidence to review: Napa County's Assessor's page describes an informal hearing before the Assessment Appeals Board at which the applicant presents their own case, or an agent — an attorney, financial professional, private appraiser, or anyone the owner designates in writing — may represent them. Build a comparable-sales table showing sale date, price, parcel, community, lot size, living area, age, and condition, weighted toward sales near the January 1, 2026 lien date. For vineyard or agricultural-preserve parcels, document planted acreage, rootstock or varietal age, and water rights or irrigation access with dated records; for hillside or wildland parcels, document access, slope, and any site conditions with dated photographs. An owner who wants to preserve the right to appeal further to Napa County Superior Court must request Findings of Fact before the hearing begins.
Current deadline guidance: 2026 regular assessment appeals: July 2 through November 30, 2026. Napa County's Clerk of the Board publishes Assessment Appeals filing rules stating that Regular Assessments must be filed between July 2 and November 30 of the current year, consistent with the California State Board of Equalization's certified 2026 county filing-period table. Assessments outside the regular filing period — supplemental, roll change, escape, or penalty — must be filed within 60 days of the date printed on the notice or tax bill or its postmark, whichever is later, and a calamity reassessment must be filed within 180 days of that date.
Napa County's Clerk of the Board sets the same July 2 through November 30 regular filing window each year, consistent with the Board of Equalization's 2026 certified county table.
Napa's revised fees, effective January 6, 2025, charge $75 per appeal for residential properties and $150 per appeal for commercial or business properties, non-refundable.
The Clerk of the Board's page states that an incomplete application or a missing required fee will result in rejection rather than partial processing.
Napa County's valley floor is largely protected agricultural-preserve vineyard land between the Mayacamas and Vaca mountain ranges, framing the city of Napa and towns such as St. Helena and Calistoga.
Official filing authority: Napa County Clerk of the Board, Assessment Appeals. https://www.napacounty.gov/1415/Assessment-Appeals
Source: Napa County Clerk of the Board, Assessment Appeals, https://www.napacounty.gov/1415/Assessment-Appeals. Reviewed 2026-09-22.
Source: Napa County Assessor-Recorder-County Clerk, Assessment Appeals Process, https://www.napacounty.gov/154/Assessment-Appeals-Process. Reviewed 2026-09-22.
Source: California State Board of Equalization, Letter to Assessors 2026/023: 2026 Assessment Appeal Filing Periods, https://boe.ca.gov/proptaxes/pdf/lta26023.pdf. Reviewed 2026-09-22.
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