California Code, Civil Code - CIV § 1798.89

(a) Unless otherwise required to do so by state or federal law, no person, entity, or governmental agency shall present for recording or filing with a county recorder a document that is required by any provision of law to be open to the public if that record displays more than the last four digits of a social security number. Unless otherwise authorized by state or federal law, a document containing more than the last four digits of a social security number is not entitled for recording.

(b) A recorder shall be deemed to be in compliance with the requirements of this section if he or she uses due diligence to truncate social security numbers in documents recorded, as provided in Article 3.5 (commencing with Section 27300) of Chapter 6 of Part 3 of Division 2 of Title 3 of the Government Code.

(c) This section shall not apply to documents created prior to January 1, 2010.