Cal. Bus. & Prof. Code § 7048
This chapter does not apply to any work or operation on one undertaking or project by one or more contracts, the aggregate contract price which for labor, materials, and all other items, is less than five hundred dollars ($500), that work or operations being considered of casual, minor, or inconsequential nature.
This exemption does not apply in any case wherein the work of construction is only a part of a larger or major operation, whether undertaken by the same or a different contractor, or in which a division of the operation is made in contracts of amounts less than five hundred dollars ($500) for the purpose of evasion of this chapter or otherwise.
This exemption does not apply to a person who advertises or puts out any sign or card or other device which might indicate to the public that he or she is a contractor or that he or she is qualified to engage in the business of a contractor.
Ca. Bus. and Prof'l. Code § 7048