California Code, Revenue and Taxation Code - RTC § 46201

(a) If the board is dissatisfied with the return filed or the amount of fee paid to the state by any feepayer, the board may compute and determine the amount to be paid, based upon any information available to it. One or more deficiency determinations may be made of the amount of fee due for one or for more than one period. When a business is discontinued, a determination may be made at any time thereafter, within the period specified in Section 46204, as to liability arising out of that business, irrespective of whether the determination is issued prior to the due date of the liability as otherwise specified in this part. In making a determination, the board may offset overpayments for a period or periods against underpayments for another period or periods and against the interest and penalties on the underpayments.

(b) The amount of fee so determined shall bear interest at the modified adjusted rate per month, or fraction thereof, established pursuant to Section 6591.5, from the date the amount of the fee, or any portion thereof, became due and payable until the date of payment.

(c) If any part of the deficiency for which a determination of an additional amount due is made is found to have been occasioned by negligence or intentional disregard of this part or regulations adopted pursuant thereto, a penalty of 10 percent of the amount of the determination shall be added, plus interest as provided in subdivision (b).

(d) If any part of the deficiency for which a determination of an additional amount due is made is found to be occasioned by fraud or an intent to evade this part or regulations adopted pursuant thereto, a penalty of 25 percent of the amount of the determination shall be added, plus interest as provided in subdivision (b).