California Code, Revenue and Taxation Code - RTC § 996

(a) Returnable containers shall be assessed only to the person in possession thereof on the lien date, provided such person is not under a legally enforceable duty to return the containers for reuse.  For the purpose of this section, a person is not under a legally enforceable duty to return returnable containers for reuse merely because such person has the right to return such containers at his election for a sum of money equal to the deposit or similar charge paid by him upon his acquisition of the containers.

(b) If a deposit or similar charge is paid by the buyer of the contents with respect to returnable containers assessable in the manner provided by this section, the cash value of such returnable containers after initial use shall be the cost of such containers, less depreciation, but shall not be less than the deposit or similar charge.

(c) As used in this section the term “returnable containers” means containers used to package soft drink beverages and of a kind customarily returned by the buyer of the contents for reuse.