When the normal wholesale price of the imports prevailing at the place of purchase cannot be ascertained by the Customs，the duty-paying value shall be assessed on the basis of the normal domestic wholesale price of similar goods prevailing at the place of importation at the time of application minus the import duty and product tax(or value added tax)paid at importation and normal freight，storage fee and other business expenses incurred after importation． When the normal domestic wholesale price of similar goods can’t be ascertained，or the business transaction of a special nature，the duty-paying value shall be assessed by the Customs．