(1) The board of commissioners may, by ordinance passed by unanimous vote, change the due date and delinquent date of all taxes, and may provide for the semiannual payment of taxes and a discount for the prompt payment of such taxes.
(2) In case a semiannual installment of taxes is made due and payable before the assessment and levy of taxes in the city for the current year is complete, the amount of the installment so collected as a tax upon any property shall be not more than fifty percent (50%) of the taxes levied on the property for the preceding year, such installment to be credited on the current year's taxes when determined and levied.