California Code, Revenue and Taxation Code - RTC § 6293

(a) Except when the sale is by lease, when a vehicle subject to identification under Division 16.5 (commencing with Section 38000) of the Vehicle Codeor a vehicle that qualifies under the permanent trailer identification plate program pursuant to subdivision (a) of Section 5014.1 of the Vehicle Code, is sold at retail by other than a person licensed or certificated pursuant to the Vehicle Code as a manufacturer, remanufacturer, dealer, dismantler, or lessor-retailer, subject to Section 11615.5 of the Vehicle Code, or a person required to hold a seller's permit pursuant to Article 2 (commencing with Section 6066) of Chapter 2 by reason of the number, scope, and character of his or her sales of those vehicles, the retailer is not required or authorized to collect the use tax from the purchaser, but the purchaser of the vehicle shall pay the use tax to the Department of Motor Vehicles acting for and on behalf of the board pursuant to Section 38211 of the Vehicle Code.

(b) If the purchaser makes an application to that department which is not timely, and is subject to penalty because of delinquency in effecting identification or transfer of ownership of the vehicle, he or she then becomes liable also for penalty as specified in Section 6591 of this code, but no interest shall accrue.

(c) Application to that department by the purchaser relieves the purchaser of the obligation to file a return with the board under Section 6452.

(d) If the purchaser does not make application to that department, or does not pay the amount of use tax due, or files a return with the board under Section 6455 which is not timely, interest and penalties shall apply with respect to the unpaid amount as provided in Chapter 5 (commencing with Section 6451).