Additional U.S. Rules of Interpretation
The Additional U.S. Rules of Interpretation are four rules unique to the HTSUS that supplement the international General Rules of Interpretation. They address use-based tariff provisions, the meaning of “of” a material in heading text, classification by use at the time of importation, and competing use provisions — and apply exclusively in U.S. import classification.
In Detail
Rule 1(a) — Use provisions: When a heading or subheading uses a use-based phrase such as "of a kind used for," "designed for use with," or "principally used in," Rule 1(a) directs classification by the principal use of that class or kind of goods in the United States. The analysis is not based on the specific importer's intended use but on the general commercial principal use of the product class in the U.S. market. A product that is principally used for one purpose classifies under the use provision for that purpose even if an individual buyer intends a different use.
Rule 1(b) — "Of" a material: Any HTSUS reference to "goods of" a particular material covers goods wholly composed of that material and may also cover goods in which the material is the chief value or gives the essential character, depending on context. This rule prevents the narrow reading that "of plastics" means only 100% pure plastics, extending the provision to goods where plastics are the dominant material.
Rule 1(c) — Use at time of importation: Goods designed for a particular use are classified by that intended use as presented at importation, even if they could theoretically be used for other purposes. Rule 1(d) — Competing use provisions: When two or more use-based headings apply to the same good, the more specific use provision controls, following the same principle as GRI 3(a).
Classification Significance
The Additional U.S. Rules matter most in HTSUS chapters where headings are defined by use — agricultural equipment, sporting goods, medical devices, professional tools, and certain textile and chemical categories. Classifiers working in these chapters must apply Rule 1(a) to determine principal use rather than relying on product description alone. Failure to apply these rules in use-provision headings is a documented source of classification error that generates audit exposure.
How Kanon Handles This
Kanon captures intended use and product class as attributes during intake and evaluates them against applicable use provisions in the HTSUS. Where a heading requires principal use analysis under Rule 1(a), Kanon documents the provision, the product class, and the basis for the principal use determination in the Classification Support Package.