The Assessor first determines the new value of the property based on current market values. The Assessor then calculates the difference between the new value (set at the time of purchase or completion of new construction) and the old value (set on January 1 of the previous fiscal year). The result is the supplemental assessment value. Once the new assessed value of your property is determined, the Assessor will send you a notification of the amount to be assessed.
- New value at date of purchase or completion of new construction $120,000
- Assessed value for current fiscal year $100,000
- Supplemental assessment value will be $20,000
This reassessment usually results in an increase in property value, in which case your supplemental taxes will be calculated by the Auditor-Controller based on the change in value, and one or more supplemental tax bills will be created and mailed to you by the Tax Collector. However, in some instances the reassessment results in a reduction in value, in which case a refund will be prepared by the Auditor-Controller and mailed to you. A reduction in value will not reduce the amount due on the annual secured tax bill. The annual tax bill must be paid in the amount originally billed.
The supplemental tax bill is usually sent directly to you. If you purchase and then sell property within a short period of time, the supplemental tax bill you receive should cover only those months during which you owned the property, and the new owner should receive a separate supplemental tax bill. However, because of the large number of parcels and frequency of property changing hands, there are often delays in placing new assessments on the roll. Be sure to check the dates used to prorate the bill to ensure that the period covered is the period during which you actually owned the property. If you think there’s an error in the pro-ration of your supplemental tax bill, please contact the AuditorController’s Office at (925) 646-2236.