Harmonized System Convention

Contracting parties, about 160 countries plus the EU, must use all HS headings and six-digit subheadings, the General Interpretative Rules and section and chapter notes without change, adding national digits only beyond six. The WCO revises the nomenclature roughly every five years; HS 2028, with 299 sets of amendments and 1,229 headings, takes effect January 1, 2028. Traders must classify each product under these rules on customs declarations.

Every customs declaration, commercial invoice and duty quote starts with an HS code, so the Convention underpins landed cost calculation for any cross-border order. Because the first six digits are identical worldwide, a 3PL can map a SKU once and reuse it for US HTS, EU CN and UK tariff lookups, extending the code only for national digits. Wrong codes cause wrong duties and customs holds; for example, classifying a smartwatch as a watch rather than a communication device changes the duty rate. Teams should plan reclassification work before HS 2028 takes effect.

• Harmonized System CodeHS CodeSix-digit international product code
• Harmonized Tariff ScheduleHTSUS product codes that set import duty rates
• Landed CostTotal cost to get a product ready to sell

• U.S. Adoption of the Harmonized System1989 · The US moves its tariff schedule to HS codes

• Revised Kyoto Convention1999, in force 2006 · WCO blueprint for modern, simplified customs procedures
• Kyoto Convention (Customs)1973, in force 1974 · 1973 treaty on simplifying customs procedures

1. WCO: What is the Harmonized System (HS)? wcoomd.org
2. WCO: Amendments effective from 1 January 2028 wcoomd.org