(a) “Spouse” means the person married to the participant on the date the participant files a beneficiary designation, or an application for a benefit, or on the date of the participant’s death.
(b) Except as excluded in Sections 26004 and 27406, a person who is the registered domestic partner of the participant, as established pursuant to Section 297 or 299.2 of the Family Code, on the date the participant files a beneficiary designation or an application for a benefit, or on the date of the participant’s death, shall be treated in the same manner as a spouse.