Cal. Code Regs. tit. 18 § 13554
If community property is converted by the spouses into the joint tenancy property of themselves and a third person, and the tenancy is thereafter maintained, upon the death of any one of the tenants on or after September 11, 1957, the effective date of Revenue and Taxation Code Section 13557, each spouse is deemed to have contributed one-half of the joint tenancy property out of his or her own separate property, and the property is or is not subject to the Inheritance Tax Law to the extent specified in Revenue and Taxation Code Section 13671. (See also Section 13671.1).
If community property acquired on or after July 29, 1927, is converted by the spouses into the joint tenancy property of themselves and a third person, and the tenancy is thereafter maintained, upon the death of any one of the tenants prior to September 11, 1957, each spouse is deemed to have contributed one-half of the joint tenancy property out of his or her own separate property, and the property is or is not subject to the Inheritance Tax Law to the extent specified in Revenue and Taxation Code Section 13671. (See also Section 13671.1).
If community property acquired prior to July 29, 1927, is converted by the spouses into joint tenancy property between themselves and a third person, and the tenancy is thereafter maintained, upon the death of one of the tenants prior to September 11, 1957, the husband is deemed to have contributed the entire joint tenancy property out of his own separate property, and the property is or is not subject to the Inheritance Tax Law to the extent specified in Revenue and Taxation Code Section 13671, except that upon the death of the husband the wife is entitled to a community exemption in the amount of one-half of the joint tenancy interest to which she is entitled where the husband died prior to September 7, 1955 (the effective date of an amendment to Revenue and Taxation Code Section 13554), and a community exemption in the amount of all the joint tenancy interest to which she is entitled up to one-half of the whole community property where the husband died on or after September 7, 1955, and prior to September 11, 1957. (See also Section 13671.1).
NOTE: As to conversion of community property into joint tenancy between husband and wife, see Section 13671.50.
As to joint tenancies generally, see Section 13671 and 13671.1.
NOTE: Reference: Section 13554, Revenue and Taxation Code.
Cal. Code Regs. Tit. 18, § 13554