Reaching the correct heading in the Harmonized Tariff Schedule is only half of the journey. Once the heading has been identified using GRI 1 to 5, the classifier must complete the second stage of analysis: determining the correct subheading. General Rule of Interpretation 6 governs this stage. It ensures that the logic used for heading selection is applied again at the subheading level, with the same discipline, the same sequence of rules, and the same reliance on legal text and notes.

Many misclassifications occur because teams stop too early. They select the right heading, then mistakenly choose a subheading based on assumptions or commercial terminology instead of repeating the legal process under GRI 6. Understanding how GRI 6 functions is essential for producing accurate and audit ready HTS classifications.

What GRI 6 Actually Requires

GRI 6 directs the classifier to apply the same interpretive rules used at the heading level when selecting the correct subheading. This includes:

• Reviewing all subheading text
• Applying any relevant Section or Chapter Notes that are legally scoped to subheadings
• Applying GRI 1 through 5 again as necessary
• Ensuring that comparisons are made only within the same level of the hierarchy

The rule emphasizes that subheadings cannot be compared across different branches of the tariff. Each level must be evaluated independently based on its own legal structure.

Why Heading Selection Does Not Automatically Determine the Subheading

A correct heading ensures that the product falls within the correct broad category. But within that category, many distinctions still matter, such as:

• Material composition
• Function
• Form or configuration
• Degree of manufacture
• Specific technical attributes
• Measurement or size differences
• Commercial presentation

GRI 6 ensures that these distinctions are evaluated using legal text, not assumptions. A product may be correctly placed in a heading but misclassified within it if the subheading analysis is incomplete.

The Structure of Subheadings and Why Sequence Matters

Subheadings are arranged in a hierarchy. To classify a product correctly, the classifier must:

1. Identify the one dash subheading level
2. Confirm that the product meets its terms
3. Move to the two dash subheading level
4. Continue down the hierarchy until no further distinctions apply

Each level acts as a filter. Skipping any level or comparing across unrelated subheadings breaks the logic required under GRI 6.

How Notes Impact Subheading Classification

Just as at the heading level, Notes play a critical role. Some notes apply only to subheadings, often refining definitions or limiting the scope of specific provisions. A common mistake is overlooking a Subheading Note that changes the meaning of terms such as:

• Parts
• Accessories
• Sets
• Certain materials
• Particular uses

GRI 6 requires the classifier to rely on these notes as mandatory legal authority.

Examples of Common GRI 6 Scenarios

Situations frequently requiring careful GRI 6 analysis include:

• Items with multiple materials where the heading is clear but the subheading distinguishes by material
• Machinery with variants requiring different subheadings for different technical capabilities
• Electronic products with subheadings defined by specific functions
• Apparel where subheadings differ by fiber content or construction
• Parts that fall under a heading but must meet additional criteria to fall under a specific subheading

In each case, heading selection resolves only the first step. Subheading selection under GRI 6 provides the precision required for compliance.

Why GRI 6 Is Essential for Consistency

Companies often classify thousands of SKUs. If teams apply GRI 1 to 5 at the heading level but rely on inconsistent methods for subheadings, classification risk increases significantly. GRI 6 ensures that the legal logic behind the heading is mirrored at the subheading level, creating:

• Repeatable decisions
• Reduced ambiguity
• Alignment with audit standards
• Stronger internal controls
• Better cross team consistency

A disciplined application of GRI 6 prevents downstream errors that may not be immediately obvious but can trigger significant compliance exposure.

The Bottom Line

GRI 6 reinforces that classification is a two stage legal process. Identifying the correct heading is necessary but never sufficient. Subheading classification must follow the same structured evaluation of legal text and notes, applied step by step, and always within the correct branch of the tariff. Mastering GRI 6 ensures accuracy, consistency, and defensible classification across even the most complex catalogs.

Start a live classification workflow in Trade Insight AI to see how structured legal logic applies GRI 6 across complex product hierarchies.