The Harmonized System (HS), which is managed by the World Customs Organization (WCO), covers the entire product world in a six-digit nomenclature. This nomenclature is the basis of the customs tariffs of all states that have signed the International Convention on the Harmonized Commodity Description and Coding System. The codes of the customs tariffs of the signatory states are therefore identical up to the sixth digit. The HS consists of 97 two-digit chapters, each divided into numerous four-digit headings and six-digit subheadings.
The EU extended the HS by two digits in the Combined Nomenclature (CN), an eight-digit nomenclature both for statistical and customs tariff purposes. The CN code has to be specified on the export declaration. As a rule, it is also the commodity code to be used for Intrastat declarations.
Two more digits were added to the CN codes in the ten-digit Integrated Tariff of the European Union (TARIC, the abbreviation for the former French name "Tarif Integré Communautaire"). The TARIC is "a multilingual database integrating all measures relating to EU customs tariff, commercial and agricultural legislation" (source: website of the European Commission, directorate Taxation and Customs Union). The two additional digits are used to encode measures such as tariff quotas and tariff ceilings, duty suspensions, and anti-dumping duties.
The regulation on the CN also provides for further digits to be added to the CN or the TARIC for the purposes of encoding national measures, such as VAT and excise duty rates, or national prohibitions and restrictions. In the EU, the national customs tariff number must be specified when goods are being imported.
The HS also forms the basis of the United States national nomenclatures for customs processing, which are the Harmonized Tariff Schedule of the United States (HTS) and the Schedule B. The first six digits of the ten-digit codes in the HTS and Schedule B are the same as the six digits in the HS codes.
HTS codes are specified in entry summaries, while the Schedule B nomenclature is used for exporting goods. The two systems are managed by different authorities: The U. S. International Trade Commission (USITC) is responsible for the HTS, while the Schedule B is managed by the U. S. Census Bureau. This authority also publishes the annual foreign trade statistics.
The first eight digits of the HTS code encodes customs duties. Reduced customs duty rates may apply in addition to standard customs duty rates, depending on the country of origin. The last two digits of the ten-digit HTS codes are used primarily for statistical purposes.