Welf. & Inst. Code, § 5657

(a) The private organization or private nonprofit organization awarded a contract with the county agency to supply mental health services under this part shall provide an invoice to the county for the amount of the payment due within 60 days of the date the services are supplied, as long as that date is at least 60 days from the date the county has received distribution of mental health funds from the state.

(b) Any county that, without reasonable cause, fails to make any payment within 60 days of the required payment date to a private organization or private nonprofit organization awarded a contract with the county agency to supply mental health services under this part, for an undisputed claim which was properly executed by the claimant and submitted to the county, shall pay a penalty of 0.10 percent of the amount due, per day, from the 61st day after the required payment date.

(c) For the purposes of this section, “required payment date” means any of the following:

(1) The date on which payment is due under the terms of the contract.

(2) If a specific date is not established by contract, the date upon which an invoice is received, if the invoice specifies payment is due upon receipt.

(3) If a specific date is not established by contract or invoice, 60 days after receipt of a proper invoice for the amount of the payment due.

(d) The penalty assessed under this section shall not be paid from the Bronzan-McCorquodale program funds or county matching funds. The penalty provisions of this section shall not apply to the late payment of any federal funds or Medi-Cal funds.