GRI 6 — Subheading Classification
GRI 6 governs classification at the subheading level. After heading-level classification is resolved under GRI 1–5, GRI 6 applies those same rules by analogy to determine which subheading within the heading applies — with the critical constraint that only subheadings at the same numeric level may be compared against each other.
In Detail
The HTSUS heading structure below the 4-digit level is organized into 1-dash subheadings and 2-dash subheadings. A 2-dash subheading is a subdivision of its parent 1-dash subheading. GRI 6 requires that classification proceed level by level: among the 1-dash subheadings first, then within the correct 1-dash parent, among the 2-dash subheadings. A 1-dash subheading and a 2-dash subheading cannot be compared as alternatives — that comparison is legally impermissible under GRI 6.
GRI 6 applies the full GRI 1–5 framework by analogy at the subheading level. This means that any subheading notes applicable to the chapter are invoked at this stage — not under GRI 1, since subheading notes cannot be applied at the heading level. Section and chapter notes that are relevant to subheading language continue to apply. The legal hierarchy of notes to text applies here just as it does at the heading level.
A common error is jumping from the heading directly to a 2-dash subheading without confirming that the good falls within the correct 1-dash parent. This level-skipping produces wrong 6-digit codes even when the heading is correctly identified. In high-tariff chapters or categories with significant subheading-level duty rate variation, this error directly affects the duty owed.
Classification Significance
GRI 6 is where the 6-digit international subheading is resolved — the level at which trade statistics are compared across countries and at which most antidumping/countervailing duty scopes and many USTR exclusions operate. Errors at the GRI 6 stage do not change the heading but produce incorrect 6-digit, 8-digit, and 10-digit codes, with downstream effects on duty rates, trade remedy applicability, and AD/CVD order scope compliance.
How Kanon Handles This
Kanon's classification engine applies GRI 6 in the legally required level-by-level sequence after heading classification is resolved. Subheading notes are evaluated at the GRI 6 stage. The traversal from 1-dash to 2-dash subheadings — with each level resolved before the next is considered — is documented step by step in the Classification Support Package.