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 proration of your supplemental tax bill, please contact the auditor-controller’s office at (925) 646-2236.
Payment Deadline and Late Payment Penalties
The date on which supplemental bills become delinquent varies depending upon when they are mailed.
Penalties of 10% are added to any installment that is not paid on time, and an additional $20 charge is added to a late second installment.
The supplemental tax bill is sent in addition to the annual tax bill and the two coupons attached to it must be paid by the due date specified on them.