Cal. Code Regs. tit. 18, § 13671.1
(C) If B predeceases A and C, and A predeceases C, the tenancy continuing in existence until A's death, none of the property at B's death will be subject to the law, but all of it will be subject thereto at A's death.
EXAMPLE (2).
A, B, and C are joint tenants in property valued at $100,000, of which $50,000 was contributed by A, $25,000 by B, and $25,000 by C:
(C) If B predeceases A and C, and A predeceases C, the tenancy continuing in existence until A's death, at B's death the property will be subject to or excluded from the law in accordance with paragraph (B) of this example. At A's death $62,500 will be subject to the law, and $37,500 will be excluded.
Note: Reference: Section 13671, Revenue and Taxation Code.
Property held in joint tenancy by three or more persons is subject to or excluded from the Inheritance Tax Law to the extent specified in Revenue and Taxation Code Section 13671. This may be illustrated by the following examples, in each of which it is assumed that any property contributed by a surviving joint tenant never belonged individually to the decedent:
EXAMPLE (1).
A, B, and C are joint tenants in property valued at $100,000, all of which was contributed by A: