Cal. Gov. Code § 55704
In any case in which a legislative body, by resolution, determines that one or more retailers have been established, or will be established, in one local agency and that consumers residing in one or more other local agencies are, or will be, purchasing tangible personal property from such retailers to the extent that equity requires the revenues of such local agency be distributed in a fair and just manner to all local agencies concerned, a contract may be entered into pursuant to this article to apportion the revenue of the local agency in which such retailers are located. Each local agency desiring to become a party to such a contract, shall, by resolution, so state and name the party authorized by the local agency to sign the contract on the agency's behalf.
Ca. Gov. Code § 55704