GST registration requirement: PAN/IEC may suffice for certain importers and exporters, quote PAN in shipping documents. Registration for import and export follows CGST Act provisions applied to IGST via Section 20; Section 23 excludes from registration persons engaged exclusively in supplies of goods that are not liable to tax or wholly exempt, and in such cases the PAN (authorised as IEC) suffices. Importers, exporters and customs brokers must quote the authorised PAN in bills of entry and shipping bills for clearance.