As a prerequisite to assignment under Section 26220, the board of supervisors shall require the collection agency to furnish a bond in the sum of not less than ten thousand dollars ($10,000) payable to the county and executed by a corporate surety licensed to do business in this State for the faithful performance of the terms and conditions of the assignment. The board may order the county auditor to make periodic audits of the accounts and books of the collection agency and when so ordered the auditor shall report his findings to the board.