Rules of origin enforcement ensures preferential tariff claims are verified, certified and subject to investigation for misuse. Customs must implement negotiated tariff concessions by notifying agreed tariff rates and origin rules, advise on Rules of Origin and certification procedures, and minimise compliance costs. At clearance, Customs ensures that claims for preferential tariff treatment meet agreement conditions, that declarations supply required information and that proofs of origin are valid and authentic. For enforcement, Customs conducts detailed investigations into suspected misuse and verifies suspect documents during inquiries.