Provisional assessment: finalisation requires security adjustment and importer or exporter payment of any remaining duty shortfall. Regulation 6 prescribes finalisation of provisional assessment under section 18, allowing recovery of any shortfall by adjustment against security obtained at provisional assessment and thereafter from the importer or exporter, requires cancellation of bonds and return of security when dues are cleared, mandates speaking orders applying natural justice where final assessment contrasts with provisional assessment, requires recorded acceptance and written notice where final assessment confirms provisional assessment, and directs electronic finalisation on the customs automated system.