28 CCR §1300.71(b)(5)

(5) A plan or a plan’s capitated provider shall not request reimbursement for the overpayment of a claim, including requests made pursuant to Health and Safety Code Section 1371.1, unless the plan or the plan’s capitated provider sends a written request for reimbursement to the provider within 365 days of the Date of Payment on the overpaid claim.