Chapter 99 is among the most frequently revised sections of the HTS, with changes occurring through presidential proclamations, USTR Federal Register notices, and congressional legislation. Importers should subscribe to CBP and USTR update notices, use the USITC's online HTS tool for current text, and work with a licensed customs broker to catch changes before they affect duty calculations.

Yes. A product may carry both a Section 232 overlay and a Section 301 overlay, for example, requiring the importer to report multiple Chapter 99 subheadings on the entry summary. Each applicable provision must be declared separately; failing to report all applicable overlays can result in underpayment of duties and potential penalties.