California Code, Code of Civil Procedure - CCP § 1250.250

(a) If the only interest of the county or other taxing agency in the property described in the complaint is a lien for ad valorem taxes, the county or other taxing agency need not be named as a defendant.

(b) The holder of a lien that secures a special assessment or a bond representing the special assessment shall be named as a defendant, regardless of the nature of the special assessment and the manner of collection of the special assessment.  The holder of the lien may, instead of an answer, certify to the court within 30 days after service of the summons and complaint on the holder all of the following information:

(c) A copy of the certification shall be sent by first-class mail to all parties to the proceeding at the time it is provided to the court.  The filing of the certification or answer shall be considered as a general appearance.