A customs HTS code is a 10-digit number assigned to every physical product imported into the United States, and it is what CBP uses to determine the duty rate, admissibility requirements, and trade statistics attached to that shipment. The first six digits come from the international Harmonized System maintained by the World Customs Organization and used by more than 180 countries; the last four are specific to the United States, and it is digits seven and eight, not the international portion, where the actual US duty rate lives.
This is a beginner-level explainer: what an HTS code is, how its digits are structured, where to look one up for your own product, and how it differs from the export-side Schedule B number. The separate legal question of how to decide between two headings that both seem to plausibly describe your product is covered in depth later in this guide, with a pointer to where that methodology actually lives.
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What Is a Customs HTS Code?
The Harmonized Tariff Schedule of the United States, or HTSUS, is the official classification system CBP uses to identify every category of imported merchandise and the duty treatment attached to it. Every product entering the US, from raw materials to finished goods, gets classified under one specific 10-digit HTS provision, and that number, not the product’s marketing description, is what determines how much duty is owed.
The HTSUS is maintained and published by the US International Trade Commission, and its legal text is not just the numbers: the General Rules of Interpretation, the section and chapter notes, the Additional US Notes, and the terms of the headings and subheadings themselves are what actually govern which code a product falls under.
The HTSUS itself runs to 99 chapters, grouped into 22 sections covering everything from live animals to works of art, roughly organized by material and degree of processing, from raw and unprocessed goods in the earlier chapters toward finished and increasingly complex manufactured goods later in the schedule.
How the 10-Digit HTS Code Is Structured
An HTS code builds in four layers, and each pair of digits narrows the classification further. The first two digits are the chapter, identifying the broad product category, for example machinery or textiles. The next two digits are the heading, narrowing that chapter to a specific type of product within it. Digits five and six are the subheading, the most detailed level still shared internationally.
Those first six digits, chapter, heading, and subheading together, are the internationally harmonized Harmonized System code, identical across every country that uses the HS. Digits seven and eight are the US tariff rate line, the first point where the code becomes uniquely American, and this is the level at which the actual US duty rate is set. The final two digits, nine and ten, are the statistical suffix, used by CBP and the Census Bureau to collect detailed trade data; they refine the product description further but do not change the duty rate itself.
| Digits | Level | Scope |
|---|---|---|
| 1-2 | Chapter | Broad product category (international) |
| 3-4 | Heading | Specific product type within the chapter (international) |
| 5-6 | Subheading | Most detailed internationally harmonized level |
| 7-8 | US tariff rate line | US-specific; where the duty rate is set |
| 9-10 | Statistical suffix | US-specific; trade statistics only, no duty impact |
Where to Look Up Your HTS Code
The US International Trade Commission publishes the current HTSUS and a free search tool at hts.usitc.gov, which is the authoritative source for the code text, duty rates, and chapter and section notes. A product description alone rarely lands on the right code on the first try; the notes attached to a chapter or heading frequently exclude products that would otherwise seem to fit.
Two importers describing the same physical product in different words can land on genuinely different, both defensible, HTS codes, which is exactly the scenario a binding ruling exists to resolve with certainty rather than best judgment.
Why the HTS Code Determines Your Duty Rate
Every HTS subheading carries at least one duty rate, and often three columns of them: a General rate that applies to countries with normal trade relations, a Special rate available only when the goods qualify under a specific preference program such as USMCA, and a Column 2 rate reserved for the small number of countries without normal trade relations status. Which column applies depends on country of origin and program eligibility, but which row applies depends entirely on the HTS code.
This is also where classification stops being an academic exercise. Additional duty programs, from safeguard actions to country-specific measures, are layered on top of the base HTS duty rate rather than replacing it, and they attach by HTS code, section, or chapter reference, so an incorrect classification does not just misstate the base rate, it can miss or misapply an entirely separate duty stacked on top. Importers running more than a handful of SKUs generally get more value from proper HTS classification consulting up front than from correcting a wrong code across dozens of past entries later.
Choosing Between Two Plausible Codes
It is common for a product to sit close to the boundary between two headings, especially for composite articles, kits, or anything genuinely new to the market. Resolving that is not a matter of picking whichever code carries the lower duty rate; it follows a fixed legal sequence.
That sequence is the General Rules of Interpretation, applied in order, alongside the relevant section and chapter notes. Rather than duplicate that methodology here, see our dedicated guide to the General Rules of Interpretation for how CBP and importers actually work through a genuinely close call.
HTS Code vs Schedule B Number: Not the Same Thing
The HTS code classifies goods coming into the United States and is maintained by the USITC. The Schedule B number classifies goods leaving the United States on an export filing and is maintained separately by the US Census Bureau’s Foreign Trade Division for the Automated Export System. They are not interchangeable in one direction: you cannot file an import entry using a Schedule B number.
The two do share a foundation. Both are 10 digits long, and the first six, the internationally harmonized HS subheading, are identical between an HTS code and its corresponding Schedule B number for the same product. Digits seven through ten diverge, since each set is assigned separately, by CBP and the USITC for imports and by Census for exports. An HTS code can generally be used in place of a Schedule B number on an export filing; the reverse is not true.
Where the HTS Code Fits in the Entry Process
The HTS code you determine here is what gets reported on the commodity lines of the CBP Form 7501 entry summary, and it is what CBP’s system uses to calculate the duty, and any additional duty programs, owed on that entry. Getting it right before the goods ship is far cheaper than correcting it after CBP has already assessed duty at liquidation.
For importers with a recurring catalog of products rather than a single shipment, working through classification once with a licensed customs brokerage and keeping a maintained classification database is what prevents the same product from being coded two different ways on two different entries, which is its own compliance flag.
Frequently Asked Questions
What is a customs HTS code?
It is the 10-digit number the Harmonized Tariff Schedule of the United States assigns to a specific product, and it is what CBP uses to determine the duty rate, admissibility requirements, and trade statistics for that product when it’s imported.
How many digits are in an HTS code?
Ten. The first six, the chapter, heading, and subheading, are internationally harmonized under the World Customs Organization’s Harmonized System. The last four, the US tariff rate line and the statistical suffix, are specific to the United States.
Where can I look up my product's HTS code?
The US International Trade Commission’s free search tool at hts.usitc.gov is the authoritative source for the current HTSUS text, duty rates, and the section and chapter notes that actually govern classification.
Does the HTS code determine my duty rate?
Yes. Each HTS subheading carries specific duty rates, generally a General rate, a Special rate for goods qualifying under a preference program, and a Column 2 rate for countries without normal trade relations status, and any additional duty programs also attach by HTS reference.
What's the difference between an HTS code and a Schedule B number?
An HTS code classifies goods being imported into the US and is maintained by the USITC. A Schedule B number classifies goods being exported from the US and is maintained by the Census Bureau. Both share the same first six internationally harmonized digits, but the final four digits are assigned separately and usually differ.
How do I decide between two HTS codes that both seem to fit my product?
That determination follows the General Rules of Interpretation applied in order, together with the relevant section and chapter notes, rather than a simple description match. See our General Rules of Interpretation guide for the full methodology.
