An HTS code (Harmonized Tariff Schedule code) is a 10-digit number that classifies every product imported into the United States. The first 6 digits are the international Harmonized System code; the last 4 are U.S.-specific. The HTS code determines your duty rate, eligibility for trade preferences (like USMCA), and exposure to special tariffs (Section 232, 301, 122). Misclassification is the most common cause of overpayment and the most common trigger for CBP audits.
Every product that enters the United States gets an HTS code on its entry summary. That code determines what duty rate the importer pays, whether the product qualifies for trade-agreement preferences, whether Section 232 or 301 special tariffs apply, and whether the entry passes CBP review without question.
For most SMB importers, the HTS code is whatever the customs broker put on the entry summary. Sometimes that is right. Often, after a closer look, it is not – and the difference between the right code and a “close enough” code can be 5%, 10%, or 25% in duty.
This guide walks through what an HTS code actually is, how the structure works, where to find authoritative classifications, and the most common ways importers get the code wrong.
The 10-digit structure of an HTS code
Every HTS code has the same anatomy. A worked example, using HTS 6109.10.0040 (a knit cotton T-shirt for women):
- Chapter (digits 1-2): “61” – Articles of apparel and clothing accessories, knitted or crocheted.
- Heading (digits 3-4): “09” – T-shirts, singlets, tank tops and similar garments, knitted.
- Subheading (digits 5-6): “10” – Of cotton.
- U.S. tariff line (digits 7-8): “00” – additional U.S. specificity.
- Statistical suffix (digits 9-10): “40” – Women’s or girls’.
What is “harmonized” about it
The first 6 digits – chapter, heading, and subheading – are the same in every country that follows the World Customs Organization’s Harmonized System (HS). That is roughly 200 countries. The last 4 digits are U.S.-specific. So the same shirt has the same first 6 digits in Canada, Germany, Japan, and Vietnam, but different statistical suffixes.
HS code vs HTS code – the practical answer
“HS code” usually means the 6-digit international code (Harmonized System). “HTS code” usually means the 10-digit U.S. code (Harmonized Tariff Schedule). For U.S. import filings, you need the full 10-digit HTS. For shipping documents and sometimes export filings, the 6-digit HS is sufficient.
How HTS codes determine your duty rate
Each HTS code maps to a duty rate (the “Column 1” general rate) plus any applicable special programs. Reading an HTS line in the schedule, you will see:
- General rate (Column 1, General) – the baseline MFN rate for goods from most-favored-nation trading partners.
- Special rate (Column 1, Special) – preferential rates for trade-agreement partners (USMCA, GSP, CAFTA-DR, etc.).
- Column 2 rate – punitive rate for non-NTR countries (currently only Cuba, North Korea, and a few others).
- Footnotes – add-on rates from Section 232, Section 301, Section 122, and AD/CVD orders.
Where to look up your HTS code
- USITC HTSUS online – the authoritative U.S. tariff schedule, free, searchable by keyword or chapter. Slow and dense to navigate.
- CBP CROSS – the public database of binding rulings. Searchable by keyword. Best resource for “how has CBP classified this kind of product before?”
- CBP Form 19.13 binding ruling request – the only way to get an authoritative classification answer with legal force.
- Commercial tools – flexport.com/tariffs, tariffhub, tariffstool – useful for first-pass lookups; not authoritative.
The five most common HTS classification mistakes
1. Classifying by marketing description, not technical attribute
“Athletic socks” is a marketing description. The HTS asks: knit or woven? Cotton, wool, or synthetic? Toe-construction? Each attribute moves the code. The right code may be HTS 6115.95, 6115.96, or 6115.99 depending on the answers.
2. Following the supplier’s code blindly
The supplier’s commercial invoice often shows an HS code optimized for export from their country, not import into the U.S. The first 6 digits should match; the U.S.-specific 4 digits and the duty rate are your problem to verify.
3. Mixing chapter rules and heading rules
The General Rules of Interpretation (GRIs) are 1 through 6 and apply in order. GRI 1 says: classify by the heading text and section/chapter notes. GRI 3 deals with composites and sets. Most classification disputes turn on whether GRI 1 or GRI 3 governs.
4. Ignoring the statistical suffix
The last two digits matter. They drive Census reporting, export licensing, and (occasionally) duty rate when there is a footnoted distinction at the statistical level.
5. Not refreshing classifications after a product change
A material change, a packaging change, or a function change can move the HTS. Importers who run a SKU under the same code for years often discover at audit that the product evolved and the code did not.
When to get a binding ruling
A CBP binding ruling is an official, legally enforceable answer to “what HTS code applies to my product?” It is filed under 19 CFR 177 with CBP Form 19.13. Processing typically runs 30-90 days. The ruling is binding on CBP for that specific importer and product.
Get a binding ruling when (a) the duty rate at stake exceeds about tariff engineering5k per year, (b) the classification is genuinely ambiguous between two codes with materially different rates, or (c) you are about to undertake a tariff engineering project where the design hinges on classification.
See our /how-to-get-binding-ruling-cbp/ guide for the filing walkthrough.
Frequently asked questions
How many digits is an HTS code?
10 digits for U.S. imports. The first 6 digits are the international Harmonized System (HS) code; the last 4 are U.S.-specific (8th-digit tariff line plus 9-10 statistical suffix).
Where can I look up my HTS code for free?
The USITC HTSUS online schedule (hts.usitc.gov) is the authoritative free source. CBP CROSS (rulings.cbp.gov) shows how CBP has classified similar products before. Commercial tools (flexport.com/tariffs) are useful for first-pass lookups.
What happens if I use the wrong HTS code?
You either overpay duty (most common) or underpay. Overpayment is recoverable through a Post Summary Correction or protest within 180 days of liquidation. Underpayment exposes you to penalties under 19 U.S.C. § 1592, including the duty difference plus interest plus potential civil penalties.
Who is responsible for the HTS classification – the importer or the broker?
The importer of record is legally responsible. Customs brokers act as the importer’s agent; the importer’s duty of “reasonable care” under 19 U.S.C. § 1484 is non-delegable. If the broker classifies wrong, the importer is still liable.
Can I get a binding ruling before I import?
Yes – and you should, for any classification with material duty exposure. File CBP Form 19.13 with a description of the product, samples or photos, and the proposed classification. CBP issues the ruling in 30-90 days; the ruling is binding for that importer and product.
Get started
Not sure if your HTS classification is correct? We run paid classification opinions starting at $500 per HTS code, including a binding ruling pathway if needed.