Cal. Rev. & Tax. Code § 6042

A marketplace facilitator shall be considered the seller, retailer, and dealer for each sale facilitated through its marketplace for purposes of determining whether the marketplace facilitator is required to register with the department under Chapter 2 (commencing with Section 6051), Chapter 3 (commencing with Section 6201), or under any other law that imposes a fee administered pursuant to Part 30 (commencing with Section 55001), in addition to each sale for which the marketplace facilitator is the seller, retailer, dealer, or any combination of the three, under Chapter 1 (commencing with Section 6001), or any other law that imposes a fee administered pursuant to Part 30 (commencing with Section 55001).