Start with the Santa Clara County filing window
Santa Clara County lists July 2 through September 15 each year for a regular assessment appeal. Supplemental and escape assessments generally have 60-day notice-based windows, so do not apply the regular-roll date to every notice.
Beginning June 1, 2026, Santa Clara County lists a $290 nonrefundable processing fee per residential, vacant-land, or agricultural parcel and application. Commercial, business, and multifamily property with five or more units carries a different fee, so confirm the current classification before filing.
Define the market before choosing comparable sales
Santa Clara County contains high-value but distinct markets across San Jose, the Peninsula edge, foothill communities, condominiums, planned developments, and rural sites. School access, commute pattern, view, slope, wildfire exposure, remodeling, construction age, lot utility, and property type can outweigh a simple price-per-square-foot comparison.
Start from the assessor's parcel record, then check property type, living area, improvements, ownership event, condition, land characteristics, and the value being appealed. A small and explainable comparable set is more useful than a long download of loosely related sales.
- Use relevant sales to estimate market value as of the January 1 lien date.
- Keep condominium, townhome, detached-home, luxury, and rural evidence in appropriate market segments.
- Document permitted area, accessory dwelling units, condition, renovation, slope, view, and site constraints accurately.
- Enter a total applicant opinion of value and make the exhibit set support that number.
Match the application to the assessment type
A regular decline-in-value appeal asks whether market value on January 1 fell below the taxable value. A supplemental or base-year dispute usually follows a change in ownership or new construction, while escape, calamity, and penalty assessments follow their own notices and rules.
Read the notice before selecting a box on BOE-305-AH. The filing period, value date, available remedy, and evidence can change with the assessment type, and one application should not blur unrelated issues.
Prepare for the hearing and keep taxes current
Santa Clara County may schedule a case before a Value Hearing Officer or an Assessment Appeals Board. The county warns that filing does not suspend outstanding taxes, and a temporary decline-in-value reduction generally applies only to the tax year under review rather than resetting the Proposition 13 base year.
Keep the filed application, proof of submission, assessor record, sale sheets, photographs, repair support, valuation explanation, and hearing correspondence together. Follow the county's current exchange deadlines and present the requested value as a conclusion supported by the exhibits rather than as a target chosen first.