California Code, Code of Civil Procedure - CCP § 2020.230

(a) If a deposition subpoena requires the personal attendance of the deponent, under Article 3 (commencing with Section 2020.310) or Article 5 (commencing with Section 2020.510), the party noticing the deposition shall pay to the deponent in cash or by check the same witness fee and mileage required by Chapter 1 (commencing with Section 68070) of Title 8 of the Government Code for attendance and testimony before the court in which the action is pending. This payment, whether or not demanded by the deponent, shall be made, at the option of the party noticing the deposition, either at the time of service of the deposition subpoena, or at the time the deponent attends for the taking of testimony.

(b) Service of a deposition subpoena that does not require the personal attendance of a custodian of records or other qualified person, under Article 4 (commencing with Section 2020.410), shall be accompanied, whether or not demanded by the deponent, by a payment in cash or by check of the witness fee required by paragraph (6) of subdivision (b) of Section 1563 of the Evidence Code.