California Code, Revenue and Taxation Code - RTC § 17751

(a) An election under Section 645(a) of the Internal Revenue Code for federal purposes shall be treated for purposes of this part as an election made by the executor, if any, of the estate and the trustee of the qualified revocable trust under Section 645(a) of the Internal Revenue Code for state purposes and a separate election under paragraph (3) of subdivision (e) of Section 17024.5 shall not be allowed.

(b) If the executor, if any, of the estate and the trustee of a qualified revocable trust fail to make an election under Section 645(a) of the Internal Revenue Code for federal purposes with respect to that qualified revocable trust, that trust shall be treated and taxed for purposes of this part as a separate trust, an election under Section 645(a) of the Internal Revenue Code for state purposes with respect to that trust shall not be allowed, and a separate election under paragraph (3) of subdivision (e) of Section 17024.5 shall not be allowed with respect to that trust.