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General & Ownership Information
(510) 272-3787

Business Personal Property:
(510) 272-3836

Our business hours are from 8:30AM to 5:00PM Monday through Friday except for holidays

Assessor Ron Thomsen

Assessor Ron Thomsen
Assessor Ron Thomsen

Thank you for visiting our Web site. The purpose of this site is to provide you with convenient access to assessment related information 24 hours a day, 7 days a week. On this site you will find general information regarding the property assessment process and assessment information on specific properties. After you have reviewed this site please let us know of any suggestions you may have to improve our service.


Your Alameda County Assessor is responsible for locating and identifying the ownership of more than 452,000 parcels of taxable real estate. He is responsible for placing an assessment on these real estate properties in accordance with Proposition 13. The Assessor also assesses 50,000 business personal property accounts at market value as of January 1 each year. In Alameda County the 2016-2017 assessment roll totals more than $262.6 billion.


Your Assessor also applies all legal exemptions, such as the homeowner's exemption, that lower your assessment liability prior to billing by the Tax Collector. This year, in Alameda County all types of exemptions totaled $10.3 billion.


Mr. Thomsen is committed to ensuring that the benefits of Proposition 13 and the market value decline provisions are consistently applied to every property in Alameda County. The department's mission statement is to provide competent and efficient assessment services in a manner resulting in equitable and fair treatment to all Alameda County residents. Your Assessor leads a dedicated staff of 175 employees, the lowest staffing level in his 39 year career. The department has an operational budget of $25 million and provides exceptional public service while successfully performing all mandated duties.


During his 39 years with the Assessor's Office, Ron has earned the Advanced Appraiser's Certificate issued by the State Board of Equalization. He has been a regular member of the International Association of Assessing Officers for the past 33 years. Its emphasis is to provide leadership in accurate property valuation and tax administration. Mr. Thomsen is also a past President of the California Assessors' Association and is currently a member of its Executive and Legislative Committees. A primary purpose of this Association is to promote the improvement of assessment procedures for the public good.


If you have any assessment related questions or concerns, please do not hesitate to call us. Thank you in advance for your suggestions on how we might serve you better.



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