General Rules of Interpretation: GRI 1 to 6 Explained

The General Rules of Interpretation decide every HS and HTS code. See what GRI 1 to 6 say, the order to apply them, and real CBP rulings that use them.

By HCT Systems Published 3 October 2026 8 min read

The General Rules of Interpretation (GRIs) are the six rules that decide how every product is classified in the Harmonized System, and so in the US Harmonized Tariff Schedule (HTS) and the EU Combined Nomenclature. They are short, they are applied in a fixed order, and almost every CBP classification ruling cites at least one of them. If you understand the GRIs, you understand why a code is right or wrong.

This guide is for importers, brokers and sellers who classify goods or review codes others have chosen. It explains each rule in plain English, quotes the key words from the official text, and shows how CBP has applied them in real rulings.

Key takeaways

The GRIs are applied in order. GRI 1 settles most products; later rules come in only when earlier ones do not decide.
GRI 1: classification follows the terms of the headings and the section and chapter notes. Titles have no legal force.
GRI 2 extends headings to incomplete, unassembled and mixed goods.
GRI 3 breaks ties: most specific description, then essential character, then last heading in numerical order.
GRI 4 is the fallback, GRI 5 covers cases and packing, and GRI 6 applies the rules at subheading level.
The US adds Additional U.S. Rules of Interpretation for use, parts and textile mixtures.

Where the GRIs sit

The GRIs are part of the Harmonized System maintained by the World Customs Organization, so the same six rules apply to the first six digits in every country that uses the HS. In the HTS, they are printed at the front of the schedule, followed by the Additional U.S. Rules of Interpretation. Quotations below are from HTS 2026 Revision 20, current as of October 2026.

GRI 1: headings and legal notes come first

GRI 1 opens by stating that the table of contents, the index and the titles of sections and chapters are "provided for ease of reference only". For legal purposes, classification is determined "according to the terms of the headings and any relative section or chapter notes".

In practice, this means two things:

Read the notes before the headings. Notes exclude goods, define terms and settle common disputes.
Do not classify by title. A chapter called "articles of apparel" does not cover every garment.

Two examples from the current HTS:

Chapter 61 note 5 says heading 6109 (T-shirts, singlets, tank tops) does not cover garments with a drawstring, ribbed waistband or other means of tightening at the bottom. A knitted top with a ribbed waistband is not a 6109 T-shirt, whatever the catalogue calls it.
Section XV note 1(m) excludes articles of Chapter 96 from the base metal chapters. CBP relied on it in ruling H303684 to move vacuum-insulated stainless steel bottles out of heading 7323 and into heading 9617.

Most products are classified by GRI 1 alone.

GRI 2: incomplete, unassembled and mixed goods

GRI 2 widens what a heading covers.

GRI 2(a) says a reference to an article includes that article incomplete or unfinished, provided it has "the essential character of the complete or finished article", and also the article entered unassembled or disassembled. A bicycle shipped in a flat box with its wheels detached is still classified under heading 8712, bicycles.
GRI 2(b) says a reference to a material includes mixtures and combinations of that material with others. It then sends goods of more than one material to GRI 3.

GRI 2(b) is why multi-material products so often end up at GRI 3: once a product could fall under two headings because of its materials, the tie-breakers apply.

GRI 3: choosing between two or more headings

When goods are, in the words of the rule, "prima facie, classifiable under two or more headings", GRI 3 sets three tests in order.

Rule	Test	What it means in practice
3(a)	Most specific description	A heading naming the product beats a heading naming a broad class. But headings that each cover only part of a mixed product or set are treated as equally specific.
3(b)	Essential character	Mixtures, composite goods and retail sets are classified by the material or component that gives them their essential character.
3(c)	Last in numerical order	If 3(a) and 3(b) cannot decide, use the heading that occurs last among those that equally merit consideration.

A real GRI 3(b) case. In ruling N363522 (August 2026), CBP classified four two-part cellphone cases made of a fibreglass-reinforced plastic rear housing with front bezels of plastic, aluminium, stainless steel or titanium. The requester proposed heading 4202 (cases and containers). CBP disagreed, citing its earlier ruling H297451, and held that the plastic gave each case its essential character because it provides the impact protection and predominates over the metal bezels, "General Rule of Interpretation 3(b) noted". The result was 3926.90.9989, other articles of plastics, at 5.3%.

Essential character is a judgement, and the factors CBP weighs (role in use, bulk, weight, value) differ from product to product. That is why composite goods and sets are where classifications most often go to review or to a ruling request.

GRI 4: goods most akin

GRI 4 applies only when GRIs 1 to 3 cannot classify the goods. They are then classified in the heading for "the goods to which they are most akin". In practice it is rarely needed, because most headings end with an "other" provision that catches what the specific headings do not.

GRI 5: cases and packing

GRI 5 settles what happens to containers that arrive with the goods.

GRI 5(a): camera cases, instrument cases, gun cases and similar containers specially shaped or fitted for a specific article, suitable for long-term use and entered with that article, are classified with it when of a kind normally sold with it. This does not apply when the container gives the whole its essential character.
GRI 5(b): packing materials and containers entered with goods are classified with the goods if they are of a kind normally used for packing them, unless they are clearly suitable for repetitive use.

A fitted case sold with binoculars goes with the binoculars. A decorative tin that is worth more than the tea inside it may not.

GRI 6: the same logic at subheading level

GRI 6 states that classification in the subheadings of a heading follows the terms of those subheadings and any subheading notes, applying the earlier rules "mutatis mutandis", with one key limit: "only subheadings at the same level are comparable". You first choose between the one-dash subheadings, then between the two-dash subheadings beneath the one you chose, and so on down.

This is why CBP rulings so often say a product is classified "by application of GRIs 1 and 6": GRI 1 picks the heading and GRI 6 walks down to the subheading. Ruling H303684 on insulated bottles uses exactly that formula.

The Additional U.S. Rules of Interpretation

The HTS adds national rules that apply only to the US schedule. In summary:

Rule 1(a): where a provision depends on use (other than actual use), the controlling use is the principal use in the United States of goods of that class or kind.
Rule 1(b): where a provision depends on actual use, that use must be intended at import, carried out, and proved within 3 years of entry.
Rule 1(c): a provision for parts covers products solely or principally used as parts of an article, but a general "parts" provision does not beat a specific provision for that part.
Rule 1(d): the Section XI principles on textile mixtures apply wherever a textile material is named. Under Section XI note 2, a mixture is classified as if it consisted wholly of the fibre that predominates by weight.

For apparel, rule 1(d) and the chief-weight test often decide the subheading. See how the HTS code for T-shirts changes with the fibre content.

Applying the GRIs in a real workflow

A practical sequence for any product:

Describe the product fully: materials with percentages, construction, function, user.
Find candidate headings and read the section and chapter notes (GRI 1).
If more than one heading remains, apply GRI 2 and then GRI 3, in order.
Walk down the subheadings level by level (GRI 6), then pick the US statistical suffix.
Check how CBP ruled on similar goods, as described in our guide to CBP binding rulings.

Our step-by-step guide on how to find HTS code numbers puts this sequence into a full worked example.

Where automation fits

HTS Pilot builds the GRIs and legal notes into its lookup. A rule engine excludes or penalises codes that the notes and heading terms rule out (for example, knitted goods cannot fall in Chapter 62) before the language model sees them, and it adds guidance such as GRI 3(b) for composite goods. Multi-material goods, sets, parts and unfinished goods are flagged for human review rather than decided automatically. Results are suggestions for reference, not official classification decisions.

Summary

The General Rules of Interpretation are a sequence, not a menu. Start with the heading terms and notes, move to GRI 2 and 3 only when you must, and use GRI 6 to walk down the subheadings. When a classification is disputed, the argument almost always comes down to which rule applies and in what order, so cite the rule, the note and the ruling in your records.

Frequently asked questions

What are the General Rules of Interpretation?

They are six rules at the front of the Harmonized System that govern how every product is classified. They come with the HS itself, so every country using the system applies the same rules to the first six digits. In the US schedule they sit before Chapter 1, followed by the Additional U.S. Rules of Interpretation that apply only to the HTS.

Do you have to apply the GRIs in order?

Yes. GRI 1 always comes first: the terms of the headings and the section and chapter notes. You only move to GRI 2 and then GRI 3 when the earlier rules do not settle the heading. GRI 4 is a last resort, GRI 5 deals with cases and packing, and GRI 6 repeats the process at the subheading level.

What does essential character mean under GRI 3(b)?

It is the material or component that gives a mixed or composite product, or a retail set, its identity. CBP looks at factors such as the role of each part in the product's use, bulk, weight and value. In ruling N363522, CBP found the plastic shell gave a cellphone case its essential character over its metal bezel.

What is the difference between GRI 1 and GRI 6?

GRI 1 decides the four-digit heading from the heading terms and the legal notes. GRI 6 applies the same logic inside that heading to choose the subheading, and it adds one condition: only subheadings at the same level can be compared. CBP rulings often state that a product is classified by application of GRIs 1 and 6.

Sources

The official texts and pages this article relies on. Check them for the current version before you act.

General Rules of Interpretation and Additional U.S. Rules, HTS 2026 Revision 20 - USITC hts.usitc.gov
HTS Chapter 61, 2026 Revision 20 - USITC hts.usitc.gov
HTS Chapter 50 with Section XI notes, 2026 Revision 20 - USITC hts.usitc.gov
CBP ruling N363522: classification of four cellphone cases rulings.cbp.gov
CBP ruling H303684: insulated stainless steel bottles, GRIs 1 and 6 rulings.cbp.gov
What is the Harmonized System (HS)? - World Customs Organization wcoomd.org

This article is general information, not legal advice and not a classification decision. Tariff texts, rates and rulings change: check the current official sources, and ask the customs authority for a binding ruling where the answer matters.