When payment is made for any real or personal property taxes or special assessments, payments must be applied first to the oldest unpaid delinquent taxes or special assessments due, if any, shown to exist upon the property for which the tax payments are made, including any penalty and interest. The discounts applicable to payment of taxes set out in section 57-20-09 do not apply to payment of taxes made on property upon which tax payments are delinquent.