California Code, Revenue and Taxation Code - RTC § 7726

(a) If any person becomes a supplier without first securing a license, the tax, applicable penalties and interest, if any, become immediately due and payable on account of all motor vehicle fuel removed, sold, or entered by the supplier.

(b) The board shall forthwith ascertain as best it may the amount of motor vehicle fuel removed, sold, or entered and shall determine immediately the tax on the amount, adding to the tax a penalty of 25 percent of the amount of the tax, and shall give the unlicensed supplier notice of this determination as prescribed by Section 7671; provided, however, that where the board determines that failure to secure a license was due to reasonable cause, the penalty may be waived. The provisions of Sections 7699 and 7700 shall be applicable with respect to the finality of the determination and the right of the unlicensed supplier to petition for a redetermination.