In case of highway improvements by the county, claims shall be filed with the county auditor of the county letting the contract. In case of contracts for improvements on the farm-to-market highway system paid from farm-to-market funds, claims shall be filed with the auditor of the state department of transportation.
But no claims filed for credit extended for the personal expenses or personal purchases of employees for their individual use shall cause any part of the unpaid funds of the contractor to be withheld.