Two importers can buy the same stainless steel bracket from the same Thai factory and pay different duty rates, because one classified it as a mounting of base metal and the other as a part of a machine. Classification is where duty is decided, and it is your legal responsibility — not your broker's.
Reasonable care is the standard
Under the Customs Modernization Act, the importer of record must use reasonable care to declare the correct HTSUS code, value, and origin. Delegating to a broker does not transfer the liability. Penalties under 19 U.S.C. 1592 run from negligence (up to 2x the duty loss) to fraud (up to the domestic value of the goods).
How the code is actually built
A US classification is ten digits:
| Digits | Meaning |
|---|---|
| 1–6 | International HS subheading — same in Thailand and the US |
| 7–8 | US tariff rate line — determines the duty rate |
| 9–10 | Statistical suffix — reporting only |
Because digits 1–6 are harmonised, your Thai supplier's export declaration is a useful cross-check. It is not authority: Thai exporters classify for Thai export purposes and are often wrong for US entry.
The General Rules of Interpretation
Work through the GRIs in order — you cannot skip ahead:
- GRI 1 — Classify by the terms of the headings and any section or chapter notes. Most goods stop here.
- GRI 2 — Incomplete or unassembled goods take the code of the finished article; mixtures go to GRI 3.
- GRI 3 — Where two headings apply: (a) the more specific description wins, (b) otherwise the essential character governs, (c) otherwise the last in numerical order.
- GRI 4 — Most akin goods.
- GRI 5 — Cases and packing.
- GRI 6 — Apply the same logic at subheading level.
For a Thai-made rubber-and-steel vibration mount, GRI 3(b) essential character usually decides between Chapter 40 and Chapter 73 — and the duty difference is real money at volume.
Use CROSS before you guess
CBP publishes every ruling it has issued in the CROSS database (rulings.cbp.gov). Search your product in plain language. You will often find a ruling on a nearly identical article with the reasoning spelled out. A prior ruling on someone else's goods is not binding for you, but it tells you how CBP thinks and is strong evidence of reasonable care if you follow it.
When to request a binding ruling
File an eRuling request with CBP's National Commodity Specialist Division when:
- Annual duty exposure on the SKU exceeds roughly USD 15,000
- Two codes are plausible and the rate spread is more than 3 points
- The product is novel, composite, or a kit
- You plan to claim a preference or exclusion that hinges on classification
The request is free. Typical turnaround is 30 days for eRulings. You submit a full description, materials breakdown, photos, drawings, and your proposed code with reasoning. The result binds CBP at every US port, which also protects you from inconsistent treatment between Long Beach and Savannah.
Do not request a ruling if you already know the answer and dislike it. Rulings are public and binding both ways.
A workable process for a Thai program
- Get a full material and function description from the factory, in writing.
- Draft a code yourself using the HTSUS and GRIs.
- Search CROSS for comparable rulings.
- Send your draft plus reasoning to your customs broker for review — ask them to argue against it.
- For high-volume SKUs, file the eRuling before the first shipment.
- Record the decision and its basis in a classification database, with the date and the person responsible.
- Re-check annually — the HTSUS is revised, and so are exclusion lists.
That last step matters in 2026: tariff actions and exclusion notices move frequently, and a code that was 0% two years ago may now carry an additional rate.
Read alongside our HS code guide, duty and tariff guide, and Section 301 workaround analysis.
FAQ
Can I just use the HS code my Thai supplier puts on the invoice?
No. Use it as a cross-check on the first six digits only. The Thai exporter classifies for Thai export statistics and has no liability for your US entry. The last four digits, and often the correct heading itself, must be determined against the HTSUS by you as importer of record.
Who is legally responsible if the classification is wrong?
The importer of record. Customs brokers act on your instructions and their errors do not shift liability away from you. This is why written classification decisions, broker review, and binding rulings are worth documenting — they evidence reasonable care if CBP challenges an entry.
How much does a CBP binding ruling cost and how long does it take?
An eRuling request is free. CBP's National Commodity Specialist Division normally responds within about 30 days for electronic requests. You provide a detailed description, materials breakdown, photographs, drawings, samples if requested, and your proposed classification with reasoning.
Is a ruling issued to another importer binding for my goods?
No, but it is highly persuasive. If CROSS shows a ruling on a substantively identical article, following it demonstrates reasonable care. If your product differs in a way that could change the outcome, request your own ruling rather than assuming the analogy holds.
What happens if CBP disagrees with a code I have used for years?
CBP can issue a Notice of Action (CBP Form 29) and rate-advance the entry, and it may look back five years. Duty, interest, and potential negligence penalties apply. A prior disclosure filed before CBP starts an investigation substantially limits the penalty exposure.
Does classification affect anything other than duty?
Yes. The code drives partner government agency flags — FDA, CPSC, EPA, USDA — quota and licensing requirements, eligibility for trade preferences and exclusions, and country-of-origin marking rules. A wrong code can cause a hold even when the duty rate happens to be identical.