CBP applies a 'substantial transformation' test: if the imported chassis undergoes processing in the US that creates a new and different article of commerce with a distinctive name, character, and use, the finished vehicle may be considered US-origin for marking purposes. However, the chassis itself retains its foreign origin for tariff purposes at the time of importation, and the correct HTS classification and applicable duties apply at that point.

Truck bodies and chassis imported separately are classified under their own HTS provisions as parts or incomplete vehicles, which may carry different duty rates than a complete, assembled truck. Importers sometimes structure shipments as separate body and chassis entries for commercial or logistical reasons, but CBP scrutinizes such arrangements to ensure they are not structured solely to obtain a lower duty rate on what is effectively a complete vehicle.