California Code, Probate Code - PROB § 37

(a) “Domestic partner” means one of two persons who have filed a Declaration of Domestic Partnership with the Secretary of State pursuant to Division 2.5 (commencing with Section 297) of the Family Code, provided that the domestic partnership has not been terminated pursuant to Section 299 of the Family Code.

(b) Notwithstanding Section 299 of the Family Code, if a domestic partnership is terminated by the death of one of the parties and Notice of Termination was not filed by either party prior to the date of death of the decedent, the domestic partner who survives the deceased is a surviving domestic partner, and shall be entitled to the rights of a surviving domestic partner as provided in this code.