Resins are generally classified in HTS Chapter 39 by polymer type and form (e.g., polyethylene, polypropylene in primary forms), while synthetic rubbers fall under Chapter 40, distinguished by monomer composition and vulcanizability. The distinction matters because duty rates, Section 301 applicability, and statistical reporting can differ significantly between the two chapters.

Certain resin and synthetic rubber imports from China are subject to Section 301 tariffs, and some specific products have faced antidumping or countervailing duty orders. Importers should verify the applicable trade-remedy status at the 10-digit HTS level for each specific product and origin before entry.