Certificate of origin requirements govern preferential tariff treatment, refund claims, and correction of incorrect import information. Preferential tariff treatment requires presentation of the Certificate of Origin, supporting documentation, and other required papers with the import declaration. If the original proof of origin is not produced, the Customs Administration may deny preferential treatment and require a guarantee or other protective measures. Excess duties may be refunded where goods would have qualified as originating goods, subject to application within the prescribed period and a formal declaration by the importer. Incorrect information affecting the Certificate of Origin must be corrected, with duty and applicable penalties paid.