Tariff Classification Under the HTSUS: General Rules of Interpretation and Additional U.S. Rules
Classification is hierarchical. Start with GRI 1: the terms of the headings and any relevant section or chapter notes control. Only if the heading is ambiguous do you proceed. GRI 2(a) covers incomplete or unassembled articles with the essential character of a complete article; GRI 2(b) addresses mixtures and combinations. GRI 3 applies when goods are prima facie classifiable in two or more headings: 3(a) most specific description; 3(b) essential character; 3(c) heading that occurs last in numerical order. GRI 4 classifies by goods most akin; GRI 5 addresses packing materials and containers; GRI 6 applies the same analysis at the subheading level, together with the Additional U.S. Rules of Interpretation (AUSRIs) and subheading notes.
Know the three duty columns: General, Special (preferential programs such as USMCA), and Column 2 (non-normal-trade-relations rates). Chapter and section notes can override heading text and are therefore essential. Explanatory Notes are persuasive but not binding.
Traps: jumping straight to GRI 3(b) "essential character" without first applying GRI 1; ignoring a legal note that excludes the goods; confusing a statistical suffix with a legal subheading; and treating a "set" as automatically classified by its most expensive component.
Worked example/rule of thumb: A product described by a specific heading and also by a broader "parts" heading is usually classified under the specific heading at GRI 1, not by essential character. Rule of thumb: notes first, heading text second, GRI 3 only when genuinely competing headings exist.