Subheading Notes
Subheading notes are legally binding notes that apply exclusively at the subheading level of the HTSUS—governing the 1-dash and 2-dash subdivisions within a heading, not the heading itself. Unlike section and chapter notes, which govern the classification of goods into headings, subheading notes govern only the further subdivision of goods already assigned to a heading. They may only be applied after heading-level classification is resolved.
In Detail
Subheading notes appear in certain chapters to define terms or establish conditions at the 6-digit subheading level. Chapter 29 (organic chemicals) includes subheading notes that define "derivatives" for specific chemical subheadings. These notes do not affect heading-level classification—a product that classifies in heading 2902 is still classified there; the subheading note only determines which 6-digit subdivision within 2902 applies.
The critical constraint is scope. Subheading notes can only be applied under GRI 6, which governs subheading-level classification. They cannot be used to determine which heading a product belongs in. A classifier who applies a subheading note to resolve a heading-level question has committed a legal error—one that may not be apparent on the face of the entry but would be exposed in a CBP audit, protest proceeding, or binding ruling request.
Subheading notes are less common than section and chapter notes but appear in several chapters where commodity distinctions at the subheading level require additional legal precision: Chapters 22, 27, 29, 33, and 71 among others contain subheading notes that are essential to correct subheading assignment. Their relative obscurity makes them easy to overlook, and easy-to-miss notes in these chapters are a documented source of classification errors.
Classification Significance
The sequencing rule is strict: section notes and chapter notes are applied under GRI 1 to determine the heading; subheading notes are applied under GRI 6 to determine the subheading within that heading. Applying a subheading note at the heading level is a classification error with no exception. Because subheading notes are less prominent than chapter notes and confined to specific chapters, they are a frequent source of undetected errors in those chapters.
How Kanon Handles This
Kanon's classification engine enforces the legal sequencing of note evaluation. Subheading notes are parsed as part of the corpus and applied only during GRI 6 subheading resolution—never at the heading level. Every note evaluation is documented with its legal source and GRI step in the Classification Support Package.