Certificate of Origin requirement: original document must be presented to claim preferential tariff treatment or face denial or guarantees. Importers must submit an original Certificate of Origin and required supporting documents when filing an import declaration to claim preferential tariff treatment; failure to present the original may lead the importing Party's Customs Administration to deny preferential treatment, require a guarantee, or take other fiscal-protective measures, and each Party shall allow importers, under its laws and within its prescribed period, to apply for a refund of excess duties where a product would have qualified as originating.