Cal. Pub. Res. Code § 4225

The fire prevention fee determined to be due by the department under this article is due and payable at the time it becomes final, and if it is not paid when due and payable, notwithstanding the penalty imposed pursuant to Section 55042 of the Revenue and Taxation Code, a penalty of 20 percent of the fee determined to be due shall be added to the amount due and payable for each 30-day period in which the fee remains unpaid.