Customs Duty

US customs duty is calculated on the transaction value of imported goods — generally the price paid, plus assists, royalties, and proceeds of resale that accrue to the foreign seller under 19 CFR 152. CBP can challenge the declared value if it falls outside the range of comparable transactions, and First Sale valuation — using the factory price rather than the middleman price — is available for multi-tier supply chains but requires documentation. Customs duty is separate from additional tariff measures: a shipment might pay 3.5% standard duty plus 25% Section 232 plus 7.5% Section 301, all calculated on the same customs value. We cover valuation methods, assist calculations, and the ruling request process when declared value is disputed.