Rule 21. The designated officer, who is notified under sub-section (2) of Section 4 of the Act, shall ascertain whether the importer not being a dealer has paid the amount of tax due in full within the period of fifteen days from the date of entry of the Motor Vehicle into a local area or before an 1application is made for registration under the Motor Vehicles Act, 1988, whichever is earlier, by obtaining from the Assessing Authority a copy of the order in Form M3 issued by the Assessing Authority to the importer. If the importer has not paid the tax, then the designated officer shall impound the vehicle forthwith.