Office of the Assessor

The Assessor is responsible for determining the assessed value of all taxable property located in San Mateo County. With approximately 237,000 assessments each year, the Assessor Division creates the official record of taxable property (local assessment roll), shares it with the County Controller and Tax Collector, and makes it publicly available. The local assessment roll is determined by identifying, mapping, inspecting, and calculating the assessed value for all real (land and structures) and business properties. Typically, property tax is 1% of the assessed value, plus an amount to amortize voter-approved bonds and any fees for special assessments or charges such as mosquito abatement or sewer fees.

The division assesses over 221,000 units on the secured roll and 16,000 units on the unsecured roll. In addition, the Office processes approximately 50,000 transfer documents, 24,000 building permits, 143,000 exemptions and 10,000 business property statements annually.

San Mateo County claims within its boundaries a wealth of land, buildings, and taxable properties with an assessed value of more than $206 billion. The property tax revenues generated from these assets are vital to maintaining local government operations and public services.

San Mateo County - Combined Property Assessment Roll - Historical Values

Book an Appointment

The public is encouraged to utilize the  Self-service Appointment Scheduling Tool to obtain information and book in-person appointments.

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Proposition 19

The new law will make important changes to two existing statewide property tax saving programs. Click for more information.

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Find A Form

You can use DocuSign to complete and submit forms online or download pdf forms.

Assessor Forms

Assessor's Annual Report

You can find and download the Assessor's Annual Reports here.

Glossary of Terms Change of Mailing Address Assessor’s Facts and Figures Read the FAQs Residential & Commercial Property Business Personal Property Tax Saving Programs Change In Ownership Online Services Assessment Roll Summaries