Cal. Bus. & Prof. Code § 23329

If the department is not satisfied with a report required to be filed by Section 23327, it may make an additional assessment of license fees due based upon the facts contained in the report or upon any information within its possession, or that comes into its possession. An additional assessment may be made of the license fees for more than one period. In making an additional assessment the department may offset overpayments for periods against underpayments for other periods. The department shall give the licensee written notice of the additional assessment.