Take a portable laptop under 10 kg. Worldwide, its HS6 subheading is 8471.30. But on a customs declaration you never file just six digits.
United States — HTS (10 digits)
The USITC maintains the Harmonized Tariff Schedule; CBP enforces it. 8471.30 becomes a 10-digit line such as 8471.30.0100. Digits 7–8 set the US duty rate; digits 9–10 are statistical. Chapter 99 codes (e.g. Section 301) stack on top.
European Union — CN (8) and TARIC (10)
The Combined Nomenclature (8 digits) is republished every year and is what exporters and Intrastat use. Imports are declared at 10-digit TARIC level, which encodes anti-dumping duties, suspensions and quotas. One wrong digit can silently skip a 48% anti-dumping measure — or wrongly trigger it.
United Kingdom — commodity code (10)
Post-Brexit, the UK Global Tariff mirrors the EU structure but diverges in rates and measures. Check the GOV.UK Trade Tariff, not TARIC, for UK imports.
Vietnam — AHTN (8 digits)
Vietnam classifies with 8 digits under the ASEAN Harmonised Tariff Nomenclature (Circular 31/2022/TT-BTC). All ten ASEAN members share the same 8-digit structure, which simplifies intra-ASEAN trade — but MFN and FTA duty rates are set by separate national decrees.
China — 8+ digits and CIQ
China's tariff code is 8 digits extended to a 13-digit declaration code including inspection/quarantine (CIQ) digits, plus mandatory "declaration elements" describing material, function, brand and model.
The rule to remember
HS6 travels worldwide; everything after digit six is national law. Classify to HS6 with GIR reasoning first, then resolve the national line for each destination — never copy a 10-digit code from one country's schedule into another country's declaration.