Cal. Rev. & Tax. Code § 38411

If the board is not satisfied with the return or returns of the tax or the amount of tax required to be paid to the state by any person, it may compute and determine the amount required to be paid upon the basis of the facts contained in the return or returns or upon the basis of any information within its possession or that may come into its possession. One or more deficiency determinations may be made of the amount due for one or for more than one period.