Provisional assessment requires a bond and security pending verification, enabling final duty reassessment upon verification. The framework allows a proper officer to direct provisional assessment where self-assessment cannot be verified or further enquiry/tests/documents are required. The officer estimates a provisional duty; the importer/exporter must execute a bond for the difference between provisional and finally assessed duty and may be required to deposit a portion of the provisional duty. The bond requires payment of any deficiency and production of outstanding documents within the period allowed. Provisional assessments should be finalized expeditiously, ordinarily within six months, with extensions for long-term project imports.