Rules of origin compliance governs preferential tariff claims and requires verification, valid proof, and investigation when misuse is suspected. Customs must implement and enforce agreement-specific tariff, valuation and origin rules while facilitating trade: analyse agreements for revenue impact, notify agreed tariff rates and Rules of Origin, and reduce compliance costs. At clearance, verify that preferential tariff claims meet agreement conditions and domestic notification requirements, ensure valid proof of origin under CAROTAR and related provisions, and investigate suspected misuse with verification of suspect documents.