At the SITC level, MAP and DAP fall within the phosphatic NES heading (56229) because they are not superphosphates. At the HTS level, however, they have their own specific tariff lines. Importers should ensure their HTS classification matches the specific product — MAP and DAP have been subject to separate antidumping proceedings, and using an incorrect HTS line could result in underpayment of duties or misapplication of trade-remedy cash deposits.

A certificate of analysis showing the P₂O₅, nitrogen, and other nutrient percentages is the primary document for classification support. For blended products, the manufacturer's formulation sheet and a statement of intended agricultural use are also helpful. If the blend contains both phosphatic and nitrogenous components in significant proportions, the essential character determination — which nutrient predominates — will drive classification, and a binding ruling from CBP is advisable for novel or high-value blends.