California Code, Revenue and Taxation Code - RTC § 6006.5

(a) A sale of property not held or used by a seller in the course of activities for which he or she is required to hold a seller's permit or permits or would be required to hold a seller's permit or permits if the activities were conducted in this state, provided that the sale is not one of a series of sales sufficient in number, scope, and character to constitute an activity for which he or she is required to hold a seller's permit or would be required to hold a seller's permit if the activity were conducted in this state.

(b) Any transfer of all or substantially all the property held or used by a person in the course of those activities when after the transfer the real or ultimate ownership of the property is substantially similar to that which existed before the transfer.  For the purposes of this section, stockholders, bondholders, partners, or other persons holding an ownership interest in a corporation or other entity are regarded as having the “real or ultimate ownership” of the property of the corporation or other entity.

(c) A sale of property, other than hay, by a producer of hay, provided that the sale is not one of a series of sales sufficient in number, scope, or character to constitute an activity for which the producer would be required to hold a seller's permit if the producer were not also selling hay.