The aromatic designation applies when the ester group is directly attached to an aromatic ring (e.g., phenyl groups in triphenyl phosphate). Non-aromatic phosphoric esters — where the ester groups are aliphatic — fall under lines 2919905010 and 2919905050. When a compound contains both aromatic and aliphatic ester groups, the predominant structural character and GRI rules govern classification; a binding ruling from CBP is advisable for mixed-structure compounds.

Many phosphoric ester plasticizers classified in Chapter 29 have been included in Section 301 tariff actions on Chinese-origin goods. The specific lines affected and any product exclusions can change, so importers should verify current Section 301 applicability and check for any active exclusion requests or renewals with a licensed customs broker before sourcing decisions are finalized.