Cal. Rev. & Tax. Code § 1607
Before the county board makes any reduction, it shall examine, on oath, the person affected or the agent making the application touching the value of the property. A reduction shall not be made unless the person or agent attends and answers all questions pertinent to the inquiry; provided, however, in the event there is filed with the county board a written stipulation, signed by the assessor and county legal officer on behalf of the county and the person affected or the agent making the application, as to the full cash value and assessed value of the property which stipulation sets forth the facts upon which the reduction in value is premised, the county board may, at a hearing, (a) accept the stipulation, waive the appearance of the person affected or the agent and change the assessed value in accordance with Section 1610.8, or (b) reject the stipulation and set or reset the application for reduction for hearing.
Ca. Rev. and Tax. Code § 1607