(1)    In this section:

      (a)    “Local governmental unit” has the meaning given in s. 66.0713 (1) (c).

      (b)    “Public improvement” has the meaning given in s. 66.0713 (1) (d).

   (2)   Every bid received for any public improvement which is not to be paid wholly in cash shall contain a provision that all payments made in cash by the local governmental unit as provided by contract or made on special assessments are subject to a specified rate of discount. The treasurer of the local governmental unit shall issue a receipt for every payment made on any special assessment, stating the date and amount of the cash payment, the discount and the total credit including the discount on a specified special assessment. The treasurer shall on the same day deliver a duplicate of the receipt to the clerk, who shall credit the specified assessments accordingly. All moneys so received shall be paid to the contractor as provided by the contract.