California Code, Probate Code - PROB § 6600

(1) Any property or interest or lien thereon which, at the time of the decedent's death, was held by the decedent as a joint tenant, or in which the decedent had a life or other interest terminable upon the decedent's death, shall be excluded in determining the estate of the decedent or its value.

(2) A multiple-party account to which the decedent was a party at the time of the decedent's death shall be excluded in determining the estate of the decedent or its value, whether or not all or a portion of the sums on deposit are community property, to the extent that the sums on deposit belong after the death of the decedent to a surviving party, P.O.D. payee, or beneficiary. As used in this paragraph, the terms “multiple-party account,” “party,” “P.O.D. payee,” and “beneficiary” have the meanings given those terms in Article 2 (commencing with Section 5120) of Chapter 1 of Part 2 of Division 5.