The General Rules of Interpretation (GRI) explained

Classification is the single largest category on the customs broker exam, often 18 to 20 of the 80 questions, and it all runs on six rules: the General Rules of Interpretation, or GRI. If you understand nothing else about the Harmonized Tariff Schedule (HTSUS), understand these, because they decide every classification question and applying them in the wrong order is one of the most common ways candidates lose points. This guide walks through GRI 1 to 6 in plain English.

The one rule about the rules: apply them in order

The GRI are not a menu. They are a sequence. You start at GRI 1 and only move to GRI 2 if GRI 1 does not resolve the classification, then to GRI 3 only if GRI 2 does not, and so on. Reaching for GRI 3 before you have genuinely ruled out GRI 1 is the classic exam trap: the answer that “feels” right under a later rule is wrong if an earlier rule already settled it. Drilling that discipline is exactly what the GRI order drill is for.

GRI 1: headings and the Notes come first

GRI 1 is where most classifications are decided. It says classification is determined by the terms of the headings and by any relative Section or Chapter Notes. In other words: read the heading text, and read the Notes that govern that Section or Chapter, because a Note can expressly include or exclude a good and overrides what the heading appears to say on its face. The titles of Sections and Chapters are for reference only; the legal text is the heading and the Notes.

Most goods are classified right here. If the heading text plus the Notes clearly cover your good, you stop. You do not go looking for a cleverer answer further down.

GRI 2: incomplete and mixed goods

GRI 2 has two parts:

• GRI 2(a) covers incomplete or unassembled articles. An article that is incomplete or unfinished is classified as the complete article if, as presented, it has the essential character of the complete one. This is also why an unassembled bicycle is still classified as a bicycle.
• GRI 2(b) extends a heading that names a material or substance to mixtures and combinations of that material with others, and extends a heading for goods of a given material to goods partly of that material. When that widening makes a good classifiable under two or more headings, you go to GRI 3.

GRI 3: goods classifiable under more than one heading

When two or more headings each seem to apply, GRI 3 resolves it, again in order:

1. GRI 3(a): the most specific heading wins. A heading that describes the good most specifically is preferred over one that is more general.
2. GRI 3(b): essential character. If specificity does not decide it, for mixtures, composite goods, and retail sets, classify by the component that gives the good its essential character.
3. GRI 3(c): last in numerical order. If neither of the above resolves it, classify under the heading that appears last in numerical order among those equally in contention.

GRI 3 is a frequent exam battleground because judging “essential character” requires reasoning, and the tempting answer is often the wrong sub-rule.

GRI 4: goods most akin

GRI 4 is the fallback for goods that cannot be classified by any of the above: classify them under the heading for the goods to which they are most akin. In practice this rule is rarely the decisive one on the exam, because GRI 1 to 3 resolve the great majority of goods, but you should know it exists and where it sits in the order.

GRI 5: containers and packing

GRI 5 handles the packaging, not the product:

• GRI 5(a): fitted cases and containers specially shaped for a specific article (a camera case, an instrument case), suitable for long-term use and presented with the article, are classified with that article.
• GRI 5(b): packing materials and containers presented with the goods are classified with the goods if they are of a kind normally used for that packing, unless they are clearly suitable for repetitive use.

GRI 6: down to the subheading

Everything above operates at the heading level (the first four digits). GRI 6 says the same rules apply, with the necessary changes, to determine the correct subheading within a heading, comparing only subheadings at the same level. It also makes the relevant Subheading Notes and Section and Chapter Notes apply at that level. GRI 6 is how you go from the right heading to the right eight- or ten-digit classification, which is the number that actually sets the duty rate.

How this shows up on the exam

A classification question typically hands you a good and four candidate classifications. The wrong answers are usually plausible under a later GRI but defeated by an earlier one, most often by a Section or Chapter Note under GRI 1. The winning method is mechanical:

1. Read the heading text and the governing Section and Chapter Notes (GRI 1).
2. Only if unresolved, work down through GRI 2, then 3, then 4, in order.
3. Apply GRI 5 for any container or packing question.
4. Use GRI 6 to pick the correct subheading.

Because classification is both the biggest category and the most method-driven, it rewards drilling more than any other. Practice the order until it is automatic in the GRI order drill and locate the right chapter fast with the chapter locator. For how classification fits the wider exam, see the customs broker exam guide and the study plan.

Sources: the General Rules of Interpretation as published in the Harmonized Tariff Schedule of the United States (hts.usitc.gov), reviewed 2026-07-22. The GRI are a public government work; this is a plain-English summary, and the official text governs. Confirm the current wording against the live HTSUS before relying on it.