California Code, Code of Civil Procedure - CCP § 2030.070

(a) In addition to the number of interrogatories permitted by Sections 2030.030 and 2030.040, a party may propound a supplemental interrogatory to elicit any later acquired information bearing on all answers previously made by any party in response to interrogatories.

(b) A party may propound a supplemental interrogatory twice before the initial setting of a trial date, and, subject to the time limits on discovery proceedings and motions provided in Chapter 8 (commencing with Section 2024.010), once after the initial setting of a trial date.

(c) Notwithstanding subdivisions (a) and (b), on motion, for good cause shown, the court may grant leave to a party to propound an additional number of supplemental interrogatories.