Property Tax Calculations Questions

How is my tax bill calculated?


The assessed value from the Assessor’s Office is multiplied by the tax rate to get the ad valorem tax amount. The remaining amount of the bill consists of special assessments and late penalties, if applicable. Taxes and most special assessments are calculated each fiscal year, which begins on July 1st and ends June 30th.

What if I disagree with the tax bill?


If you think the value of the property is incorrect, please contact the Assessor’s Office at (925) 313-7600. The voter-approved bonds that make up the tax rate cannot be changed. If the special assessments are incorrect, please call the phone number listed to the right of the special assessment. You can also contact the districts directly at these telephone numbers.

What tax exemptions are available?


There are exemptions that will reduce your assessed value and ad valorem tax. For more information, please contact the Assessor’s Office (Exemptions Division) at (925) 313-7481. There are senior exemptions for some special assessments, which have specific criteria that must be met. Your tax bill has an asterisk next to the assessments that you may qualify for an exemption. For more information, please call the phone number listed to the right of the special assessment. You can also contact the districts directly at these telephone numbers.

How are my late penalties calculated?


For information about late penalties, please see the Tax Collector’s Notice of Power to Sell.

How can I have my late penalties reduced?


You can fill out the Tax Penalty Relief Application. For more information, please contact the Tax Collector’s Office at (925) 957-5280.

Why do I have taxes from prior fiscal years on my tax bill?


The Assessor’s Office may have increased your assessed value in prior fiscal years. That increase multiplied by your tax rate for that fiscal year equals the tax increase. If you have questions about the assessed value increase, please contact the Assessor’s Office at (925) 313-7600.