Standard import documentation includes a commercial invoice, packing list, bill of lading, and certificate of origin identifying the smelting country. For LME-registered brands, a brand certificate may also be required by the buyer. If the product is subject to antidumping or countervailing duty orders, an importer-specific cash deposit rate may apply, and CBP may request additional mill or smelter certification.

LME prices establish the transaction value basis for customs valuation, but ad valorem duties are assessed on the customs value at the time of entry. Significant price volatility between contract date and entry date can affect the dutiable value, and importers using first-sale or transaction-value methodologies should ensure their valuation approach is documented and defensible under CBP regulations.