California Code, Revenue and Taxation Code - RTC § 2922.5

Notwithstanding Section 2922, with respect to taxes on the unsecured roll where an application for reduction in assessment has been filed pursuant to Section 1607 and the board reduces the assessment in dispute, Section 4985 shall apply.

If a taxpayer does not pay by the delinquency date established by Section 2922 and indicated on the unsecured assessment roll, interest at the rate of 1 percent per month on the unpaid tax shall be charged from that date to the date of correction. Taxes unpaid by 5 p.m., or the close of business, whichever is later, on the date established by Section 4985 are delinquent and thereafter a delinquent penalty of 10 percent attaches to them.

If taxes are not paid by 5 p.m., or the close of business, whichever is later, on the last day of the second succeeding month after the 10-percent penalty attaches, an additional penalty of 1 1/2 percent attaches to them on the first day of each month thereafter until the time of payment or until the time a court judgment is entered for the amount of the unpaid taxes and penalties, whichever occurs first.

This section is not applicable to assessments made pursuant to Section 501, or to assessments made pursuant to Section 531.2 where the escape is the result of an act or omission of the assessee and to assessments made pursuant to Sections 531.3, 531.4, and 531.5.