Methodology and data sources
Every number on Dutiable comes from an official tariff schedule or a government notice. This page explains which ones, how often they are checked, and how the written guidance around them is produced.
Where the rates come from
| Market | Source | Where | Checked |
|---|---|---|---|
| United States | Harmonized Tariff Schedule (USITC) | hts.usitc.gov | Weekly, Monday 05:00 UTC |
| European Union | TARIC / Combined Nomenclature (European Commission) | ec.europa.eu/taxation_customs | Weekly, Monday 06:00 UTC |
| United Kingdom | UK Global Tariff (HMRC Trade Tariff) | trade-tariff.service.gov.uk | Weekly, Monday 07:00 UTC |
| US Section 301 | USTR notices in the Federal Register | federalregister.gov | Weekly, Monday 04:00 UTC |
| US Section 232 | Presidential proclamations and Commerce notices | federalregister.gov | Weekly, Monday 04:30 UTC |
| Other markets | National tariff schedules and customs authority pages | Linked on each country page | Reviewed by hand |
The weekly sync re-reads each schedule, compares every HS code with the last stored rate and records any difference with the date it was found. Those differences are published unedited in the tariff tracker. Pages that show a rate say when it was last verified and link to the official source so you can check it yourself.
What the rates mean
Unless a page says otherwise, a rate is the Most-Favoured-Nation (MFN) duty — what goods pay without a trade agreement. Preferential rates under free trade agreements need proof of origin, and additional duties (Section 301, Section 232, anti-dumping and countervailing duties) depend on the country of origin. US pages list those layers separately because they often exceed the MFN rate; the US tariff stack guide explains how they combine.
How reference pages and guides are written
HS code pages, country import guides and blog posts are written by Dawid, who runs Dutiable. Each classification note starts from the heading text and explanatory notes of the Harmonized System, then checks the national subheading in the US, EU and UK schedules and, for borderline products, binding rulings in CBP CROSS and the EU EBTI database. Country guides are checked against the customs authority's own pages.
Guides about fast-moving rules — US tariffs, de minimis, the EU customs reform — are re-checked against the Federal Register, CBP notices and EU legal texts when the rules change, and show the date of that check under the title. Older articles whose facts were overtaken have been merged into the current guide on the same topic rather than left online.
Where AI is used
The HS code lookup uses Google's Gemini model to suggest a classification from a plain-language product description. The suggestion is checked against the live code list, shown with a confidence score and the classification rule it relies on, and never presented as a ruling. The weekly Section 301 and 232 sync also uses an AI model to read Federal Register notices; its output is validated against a strict schema before anything is stored. Reference pages and guides are not generated automatically.
Limits
Dutiable is an information service, not a customs broker. Customs authorities make the final decision on classification and value; for high-value or disputed goods, ask for a binding ruling (US CBP ruling, EU BTI, UK Advance Tariff Ruling) or work with a licensed broker.
Corrections
If a code, rate or rule on this site is wrong, write to hello@dutiable.io or use the contact page with the page address and the source that shows the correct value. Confirmed corrections are usually live within a day.