Subheading (HTSUS)
A subheading is a 6- or 8-digit provision in the HTSUS that subdivides a heading into more specific product categories. Subheading classification is governed exclusively by GRI 6 and can only proceed after the heading-level classification has been resolved — subheadings within different headings may never be compared against each other.
In Detail
The HTSUS uses a two-tier subheading structure. First-level subheadings carry one dash (–) in their description and correspond to the internationally harmonized 6-digit level shared with all HS-based tariff schedules. Second-level subheadings carry two dashes (––) and represent U.S.-specific 8-digit provisions that further break down the 6-digit categories. The 9th and 10th digits are statistical suffixes — they are not additional classification levels.
GRI 6 establishes two procedural constraints that are frequently violated in practice. First, only subheadings at the same level of indentation may be compared against each other: a one-dash subheading and a two-dash subheading cannot be weighed against each other in a selection analysis. Second, subheading notes — which exist in certain chapters — apply only to resolve questions at the subheading level and cannot be used to answer heading-level classification questions.
When descending through subheadings, the same analytical framework used at the heading level applies: the terms of the provision, read in light of any applicable subheading notes, govern the analysis under GRI 6 by reference to GRI 1–5. A subheading beginning with “Other” or “–– Other” is a residual provision and may only be used after all more specific alternatives in the same heading have been evaluated and excluded.
Classification Significance
The 8-digit subheading is where most duty rate differentiation occurs. Trade remedy coverage — Section 301, Section 232, antidumping and countervailing duty orders — is specified at the 8-digit subheading level, not the heading level. A product correctly classified at the heading level but misplaced at the subheading level will carry the wrong duty rate and may improperly escape or incur trade remedy liability.
How Kanon Handles This
After resolving heading classification under GRI 1, Kanon descends through subheadings applying GRI 6 — comparing only same-level provisions as legally required. Subheading notes are applied at this stage and kept analytically separate from heading-level analysis. Every subheading evaluated, and the reasoning for the final selection, is captured in the Classification Support Package.