CBP applies a 'substantial transformation' test: the country where the drone undergoes its last substantial transformation — typically final assembly that creates a new and different article with a distinct name, character, and use — is deemed the country of origin. For drones assembled in Canada or Taiwan from Chinese-origin components, importers must document the assembly process carefully, as CBP may find that the essential character was imparted at the component manufacturing stage, potentially triggering Section 301 liability.

Beyond the tariff-line distinction, the 250 g threshold is operationally significant: drones above it must be registered with the FAA regardless of use, and commercial operations require Part 107 certification. This weight band also captures most professional-grade mapping, inspection, and agricultural spray drones, which carry higher unit values and more complex supply chains than consumer micro-drones, making accurate classification and valuation especially important.