California Code, Revenue and Taxation Code - RTC § 18508

(a) Returns of an estate, a trust, or an estate of an individual under Chapter 7 or Chapter 11 of Title 11 of the United States Code shall be made by the fiduciary thereof.

(b) Under the rules and regulations that the Franchise Tax Board may prescribe, a return made by one of two or more joint fiduciaries shall be sufficient compliance with the requirements of Section 18501.  A return made pursuant to this subdivision shall contain a statement that the fiduciary has sufficient knowledge of the affairs of the person for whom the return is made to enable him or her to make the return, and that the return is, to the best of his or her knowledge and belief, true and correct.