The Assessor sets the value of the tangible assets possessed by more than 15,000 businesses operating in San Mateo County, thereby establishing their taxable value. The Assessor also sets the value of 4,000 boats and 400 private aircraft owned here.

Private citizens get answers to questions about their property from the Assessor. These include how to file business personal property statements and, through the County Clerk, how to file fictitious business name statements.