California Code, Code of Civil Procedure - CCP § 2034.710

(a) On motion of any party who has failed to submit expert witness information on the date specified in a demand for that exchange, the court may grant leave to submit that information on a later date.

(b) A motion under subdivision (a) shall be made a sufficient time in advance of the time limit for the completion of discovery under Chapter 8 (commencing with Section 2024.010) to permit the deposition of any expert to whom the motion relates to be taken within that time limit. Under exceptional circumstances, the court may permit the motion to be made at a later time.

(c) The motion shall be accompanied by a meet and confer declaration under Section 2016.040.