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.
Supplemental taxes are due on the date the bill is mailed.For bills mailed July through October, the first installment becomes delinquent at 5 p.m. on December 10, and the second installment becomes delinquent at 5 p.m. on April 10.
For bills mailed November through June, the first installment becomes delinquent at 5 p.m. on the last day of the month following the billing month, and the second installment becomes delinquent at 5 p.m. on the last day of the fourth month following the date the first installment is delinquent (Rev. & Tax. Code §75.52).
NOTE: If the delinquency deadline falls on a weekend or a holiday, the penalty is waived if payment is received by 5 p.m. or at the close of business, whichever is later, on the next following business day (Code Civ. Proc. §12(a); Rev. & Tax. §75.52).
Delinquency Penalties & Costs
The date on which supplemental bills become delinquent varies depending upon when they are mailed.
Each installment carries a ten-percent delinquency penalty (Rev. & Tax. Code §75.52(c)). When the second installment becomes delinquent, a $10 cost charge attaches (Rev. & Tax. Code §75.52(d)). The penalty and the cost are included with any taxes transferred to unsecured collection, pursuant to provisions of Revenue and Taxation Code section 75.54(b).
NOTE: Unsecured bills resulting from ownership prorations made in accordance with Revenue and Taxation Code section 75.54(c) are not subject to cost charges.