California Code, Health and Safety Code - HSC § 79655

(a)(1) Until June 30, 2021, except as provided in subdivision (b), a monetary obligation to the department pursuant to this part or Chapter 6.5 (commencing with Section 25100) of Division 20 shall be subject to interest from the date of the demand at an interest rate of 7 percent per annum.

(2) Commencing July 1, 2021, except as provided in subdivision (b), a monetary obligation to the department pursuant to this part or Chapter 6.5 (commencing with Section 25100) of Division 20 shall be subject to interest from the date of the demand at an interest rate of 10 percent per annum, except that, for obligations of local governments, the interest rate shall be 7 percent per annum.

(b)(1) The department shall waive the interest described in subdivision (a) if the obligation is satisfied within 60 days from the date of invoice.

(2) If, within 45 days of receiving an invoice, the liable person provides written notice to the department in accordance with its invoice dispute resolution procedures disputing in good faith the monetary obligation specified in the invoice, or a portion thereof, the department shall waive the interest until the dispute is resolved.