How to find the HS code for your product

Every product that crosses a US border needs a classification number. Get it right and you pay the correct duty and clear customs cleanly. Get it wrong and you either overpay for years without noticing, or underpay and expose yourself to back-duties, interest and penalties. This guide walks through how to find the right code from first principles — no jargon, no shortcuts that get you in trouble.

What an HS code actually is

The Harmonized System (HS) is a global product-naming standard maintained by the World Customs Organization. The first six digits are the same in every one of the 200-plus countries that use it. The United States then adds four more digits to create the 10-digit Harmonized Tariff Schedule (HTS) number that CBP actually charges duty against.

• First 2 digits = the chapter (e.g. 61 = knitted apparel).
• First 4 digits = the heading (e.g. 6109 = T-shirts and singlets).
• First 6 digits = the international HS subheading (e.g. 6109.10 = of cotton).
• Digits 7–10 = the US statistical suffix (e.g. 6109.10.0060 = men's/boys' cotton tees).

Step 1 — describe the product the way the schedule does

Customs classification is about what a thing is, what it is made of, and what it does — not what you call it in your catalogue. Before you search, write a one-line technical description: the material (cotton, stainless steel, ABS plastic), the form (knitted, cast, assembled), the function, and who uses it. "Cozy weekend tee" is a marketing name; "men's knitted T-shirt, 100% cotton" is a classification.

Step 2 — find the chapter, then the heading

Start broad. The 99 chapters are grouped by material and then by degree of manufacture — raw materials early, finished goods later. Narrow to the chapter, then read the heading texts inside it. Headings are legal descriptions; read them literally. If a heading says "knitted or crocheted", a woven version of the same garment belongs somewhere else entirely.

Step 3 — apply the General Rules of Interpretation

When more than one heading looks plausible, the six General Rules of Interpretation (GRI) decide, in order. GRI 1 says the headings and section/chapter notes govern — read those notes, they frequently include or exclude things you would never expect. GRI 3 handles goods that could fall under two headings: classify by the heading with the most specific description, then by essential character, then by the last applicable heading. Most disputes are resolved by GRI 1 and GRI 3 alone.

Step 4 — read the notes and check for exclusions

Section and chapter notes are binding law, not commentary. A chapter note can pull a product out of the obvious heading and send it to a completely different chapter — parts of general use, sets, composite goods and "articles of plastic" are common traps. If the note excludes your product, believe the note.

Step 5 — confirm the rate on the official schedule

Once you have a candidate 10-digit line, verify the duty rate against the USITC Harmonized Tariff Schedule — the schedule of record. Never trust a rate you saw in a forum, a spreadsheet, or generated by an AI without a source. And remember the base MFN rate is rarely the whole bill: Section 301, Section 232 and other Chapter 99 measures stack on top depending on the country of origin.

• Read the general (Column 1) rate for normal-trade-relations countries.
• Check Chapter 99 for additional Section 301 / 232 duties tied to origin.
• Note the unit of quantity — some lines carry specific ($/kg) or compound rates.
• Screen for antidumping/countervailing duty orders, which can dwarf the base rate.

Common mistakes that cost real money

• Classifying by brand or use-case name instead of material and construction.
• Stopping at 6 digits — the US rate lives on the 10-digit line.
• Ignoring chapter notes that exclude your product from the obvious heading.
• Forgetting that origin, not where you bought it, drives the additional tariffs.
• Reusing a supplier's code without checking it against the current schedule.

When to get help

For a straightforward finished good, this five-step method gets you there. For sets, kits, multi-material assemblies, chemicals, or anything where a wrong guess is expensive, a licensed customs broker or a CBP binding ruling is worth it. Nothing here — and nothing PortRobin returns — is a customs ruling; it is an informational estimate to get you to the right answer faster.