Cal. Rev. & Tax. Code § 41080

If any person fails to make a return, the department shall make an estimate of the number of access lines or purchases of prepaid mobile telephony services that are subject to the surcharges. The estimate shall be made for the period or periods in respect to which the person failed to make a return and shall be based upon any information which is in the department’s possession or may come into its possession. Upon the basis of this estimate the department shall compute and determine the amounts required to be paid to the state, adding to the sum thus arrived at a penalty equal to 10 percent thereof. One or more determinations may be made for one or for more than one period.