Welf. & Inst. Code, § 14170.1

(a) Prior to the issuance to a provider of pharmaceutical services of any demand for payment pursuant to an audit or examination conducted under Sections 10722 and 14170, the amount of any underpayment to the provider for validly submitted claims or for valid claims which have inadvertently not been submitted and which arose during the audit period shall be determined and credited toward the amount of any overpayment due to the department. This section shall apply to all audits and examinations conducted under Sections 10722 and 14170 relative to amounts paid during the audit period for services provided to Medi-Cal beneficiaries. No audit may be reopened to provide for underpayments in which a final decision has been reached pursuant to Section 14171 or in which a certificate has been filed pursuant to Section 14172.

(b) When a provider of pharmaceutical services asserts that a claim has been underpaid for purposes of receiving a credit against overpayments, as authorized by this section, the provider shall submit to the department information and documentation sufficient to resolve any dispute as to whether such claim was in fact underpaid.

(c) For purposes of this section, the term “underpayments” shall include errors made by the pharmacist and errors made by the fiscal intermediary in determining payments for claims submitted within the billing time limits specified in Section 14115.