When a married couple uses community funds to acquire property with joint tenancy title, the property is presumptively held as community property if acquired after January 1, 1975.  (See Fam. Code 760.)  The spouses hold joint tenancy interests in property acquired before 1975 as separate property.  For joint tenancy property acquired between January 1, 1975, and December 31, 1984, the act of taking title as joint tenants is, in itself, insufficient to prove a transmutation; however, a court may consider the manner of taking title in determining whether the spouses had an oral agreement or common understanding.  For joint tenancy acquired after January 1, 1985, joint tenancy titling of property acquired by spouses using community funds is not sufficient by itself to transmute community property into separate property.  There must be some other written express declaration by the adversely affected spouse to transmute the property to separate joint tenancy property.  (Fam. Code, 852.)

See In re Brace (9th Cir. 2020) (Applying the California Supreme Court’s answers to its certified questions, the Ninth Circuit holds that one of the properties acquired by the debtor and his non-debtor spouse was purchased after 1972 and thus is community property, all of which is an asset of the bankrupt estate.  The acquisition date of the other property is not clear from the record.  If acquired before 1972, it could be separate property in which case the debtor’s estate would include only the debtor’s one-half joint tenancy interest in the property.)