California Code, Revenue and Taxation Code - RTC § 408.4

(a) The assessor shall disclose information, furnish abstracts, or permit access to all records in his or her office to designated employees of a city's finance office when conducting an investigation to determine whether a documentary transfer tax should be imposed for an unrecorded change in control or ownership of property.

(b) Upon the written request of a designated employee of a city's finance office, the assessor shall provide to the designated employee of a city's finance office information for the preparation and enforcement of Part 6.7 (commencing with Section 11901) of Division 2. The information provided by the assessor shall not include social security numbers. The designated employee of a city's finance office shall, under penalty of perjury, certify to the assessor that he or she needs the information to assist with the preparation and enforcement of Part 6.7 (commencing with Section 11901) of Division 2 and that the information provided pursuant to this subdivision that is not public record and that is not open to public inspection shall not become public record and shall not be open to public inspection.

(c) Whenever the assessor discloses information, furnishes abstracts, or permits access to records in his or her office to designated employees of a city's finance office pursuant to this subdivision, the city shall reimburse the assessor for any costs incurred as a result thereof.