Audit powers allow officers to examine assessments of import and export transactions, on-site or at office premises. Section 99A authorises the proper officer to audit assessments of imported or export goods or any auditee either in the officer's office or at the auditee's premises in the manner prescribed, and defines auditee to include importers, exporters, approved custodians, warehouse licensees and any person directly or indirectly involved in clearing, forwarding, stocking, carrying, selling or purchasing imported, export or dutiable goods.