The determining factor is the compound's intended use and regulatory status. If the substance is an active pharmaceutical ingredient (API) or drug intermediate destined for a finished drug product, FDA entry procedures apply — including foreign facility registration and, for controlled substances, DEA authorization. If the compound is imported as an industrial chemical with no drug application, TSCA certification is the standard requirement. Importers should document intended use clearly in entry records to avoid reclassification by CBP.

Acetaminophen has its own dedicated 10-digit line (2924296210), and misclassifying it under the broader aromatic cyclic amides NESOI line (2924296250 or 2924296000) can result in duty discrepancies and potential CBP penalties. Additionally, pharmaceutical-grade acetaminophen imports require FDA drug establishment registration from the foreign manufacturer and are subject to FDA port-of-entry examination, so both classification accuracy and regulatory documentation must be in order simultaneously.