HS code.

The customs classification carried by a shipment, six digits agreed internationally and extended to eight or ten nationally, which sets the duty rate and the paperwork owed at the border. Knit versus woven, and which fiber holds chief weight in a blend, each move a garment to a different code and a different rate. Since the US de minimis exemption ended, a wrong code now bites on parcels that used to cross duty-free, as a hold at the border or a bill afterwards.