Recovery of duty: officials may invoke bonds to recover unpaid duty plus interest when exemption conditions are breached. Where an importer fails to comply with exemption conditions or payment obligations under rule 7, the Deputy Commissioner or Assistant Commissioner of Customs having jurisdiction where the imported goods are used shall invoke the bond and recover the difference between the duty leviable absent the exemption and any duty already paid, with interest at the rate notified under section 28AA from importation until full payment. The importer remains responsible for using goods per the exemption notification and officials may take action under these rules without prejudice to other legal remedies.