On-site Post Clearance Audit requires on-premise access to records and cooperation, enabling verification of customs self-assessment. On-site Post Clearance Audit creates an on-premise audit framework authorizing proper officers to verify correctness of customs self-assessment by requiring importers/exporters to provide books, transaction records and assistance for five years, granting officers powers to inspect goods, take samples and copies, and obliging officers to give at least fifteen days' advance notice and an opportunity to respond to objections before finalizing audit findings.