A multi-function integrated circuit classifies according to its principal function. If the device is marketed and used primarily as a processor or controller, it goes under 854231. Where principal function is genuinely ambiguous, CBP guidance and binding ruling requests are the appropriate path, as the answer affects both duty rates and any applicable Section 301 exposure.

Many advanced ICs are subject to U.S. export control regulations (EAR), and certain foreign-produced chips made with U.S. technology may trigger foreign direct product rule restrictions on re-export. Entity-list screening is essential when sourcing from or through certain jurisdictions. Importers should also verify whether specific lines carry Section 301 measures based on origin, as coverage has evolved across multiple rounds of action.