California Code, Revenue and Taxation Code - RTC § 1645

(a) If, within 30 days following receipt of the report and recommendation of the panel of hearing officers by the county board of equalization or assessment appeals board of a concerned county, the assessor of that county or the assessee submits a written request to the board to reject the recommendation of the panel of hearing officers with respect to property located in that county, the board shall, without further testimony, do either of the following:

(b) In the event that neither the assessor nor the assessee makes a request in accordance with subdivision (a) within the prescribed 30-day period, the board shall, not later than 60 days following its receipt of the report and recommendation of the panel of hearing officers, without further testimony, take the action specified in paragraph (1) or (2) of subdivision (a).

(c) In any hearing set by the board pursuant to this section, there shall be a rebuttable presumption that the recommendation of the panel of hearing officers is correct.