Rev. & Tax. Code, § 2922

(a) Taxes on the unsecured roll as of July 31, if unpaid, are delinquent at 5 p.m., or the close of business, whichever is later, on August 31 and thereafter subject to a delinquent penalty of 10 percent.

(b) Taxes added to the unsecured roll after July 31, if unpaid are delinquent and subject to a penalty of 10 percent at 5 p.m., or the close of business, whichever is later, on the last day of the month succeeding the month of enrollment.

(c) Taxes transferred to the unsecured roll pursuant to any provision of law and already subject to penalties also transferred, shall be subject only to the additional penalties and costs prescribed in subdivisions (d) and (e), which shall attach beginning July 1 and on the first day of each month thereafter.

(d) Unsecured taxes remaining unpaid at 5 p.m., or the close of business, whichever is later, on the last day of the second month after the 10-percent penalty attaches shall be subject to an additional penalty of 1 1/2 percent attaching on the first day of each succeeding month on the amount of the original tax. The additional penalties shall continue to attach until the time of payment or until the time a court judgment is entered for the amount of unpaid taxes and penalties, whichever occurs first.

(e) In addition to the penalties imposed by this section, the tax collector may collect actual costs of collection incurred by the county up to the time the delinquency is paid.

(f) When the last day of a month falls on Saturday, Sunday, or a legal holiday, any penalty to which the tax becomes subject on that date shall not attach if the tax collector receives payment in full by 5 p.m., or the close of business, whichever is later, on the next business day. If the board of supervisors, by adoption of an ordinance or resolution, closes the county’s offices for business prior to the time of delinquency on the “next business day” or for that whole day, that day shall be considered a legal holiday for purposes of this section.