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Harmonized System (HS) codes are the six-digit product codes of the World Customs Organization’s international goods nomenclature. This guide shows how a code is built, how the six General Interpretative Rules decide between headings, where national codes take over, and what changes with HS 2028. It is written for researchers and administrators who need to read, cite or merge trade data coded to the HS.
What the Harmonized System is
The Harmonized System (HS) is a multipurpose international product nomenclature developed by the World Customs Organization (WCO). The WCO describes it as comprising more than 5,000 commodity groups, each identified by a six-digit code, used by more than 200 countries and economies for customs tariffs and trade statistics, and covering over 98% of merchandise in international trade (WCO, “What is the Harmonized System”, read 2026-11-11).
The HS Convention entered into force on 1 January 1988. It consists of a Preamble, 20 Articles and an Annex, and the Annex is the nomenclature itself. Contracting Parties must align their customs tariffs and statistical nomenclatures for imports and exports with the HS, and should publish import and export statistics at the six-digit level or beyond (WCO, Harmonized System: 30 Years On). The same document lists uses beyond tariffs: international trade statistics, rules of origin, internal taxes, trade negotiations such as WTO tariff schedules and free trade agreements, transport statistics, and monitoring of controlled goods.
How a six-digit HS code is built
An HS code reads left to right from broad to specific. The first two digits give the chapter, the first four digits give the heading, and all six give the subheading (WCO, 30 Years On). The dot after the fourth digit is formatting only.
| Digits | Level | What it identifies |
|---|---|---|
| 1-2 | Chapter | Numbered 01-97, grouped into 21 Sections; Chapter 77 is reserved, leaving 96 chapters in use |
| 3-4 | Heading | The position of the heading within its chapter; the four digits together form the heading number |
| 5 | One-dash subheading | A subdivision of the heading; 0 means the heading is not subdivided |
| 6 | Two-dash subheading | A further subdivision; 0 means the one-dash subheading is not subdivided |
| 7 and beyond | National extension | Set by each country or union, not by the HS Convention |
Worked decomposition: HS 1108.13
The WCO uses potato starch as its example of a fully subdivided code. Reading 1108.13 digit by digit:
- Digits 1-2 =
11: Chapter 11. - Digits 1-4 =
1108: heading 11.08. - Digit 5 =
1: the first one-dash subheading of heading 11.08. - Digit 6 =
3: the third two-dash subheading within that one-dash subheading.
The WCO gives two simpler cases. Cucumbers and gherkins, fresh or chilled, are 0707.00: both trailing digits are 0 because heading 07.07 is not subdivided. Buckwheat is 1008.10: the fifth digit is 1 and the sixth is 0 because that one-dash subheading is not split further.
For scale, the HS 2017 edition has 1,222 headings and 5,387 six-digit groups of goods (WCO, 30 Years On).
General Interpretative Rules (GIRs): how goods are assigned to a heading
Classification is not a keyword match. Six General Interpretative Rules, applied in hierarchical order, decide which heading a product belongs to (WCO, 30 Years On, pp. 21-24). Titles of sections and chapters are for reference only; legal classification rests on the terms of the headings and the Section and Chapter Notes.
| Rule | What it does |
|---|---|
| GIR 1 | Classify by the terms of the headings and any relevant Section or Chapter Notes. Where these leave only one heading open, only GIR 1 is used at heading level. |
| GIR 2(a) | A heading for an article also covers it incomplete or unfinished if it has the essential character of the finished article, and covers it unassembled or disassembled. |
| GIR 2(b) | A heading for a material or substance also covers mixtures and combinations of it with other materials. Goods then covered by more than one heading go to GIR 3. |
| GIR 3(a) | Prefer the heading with the most specific description. |
| GIR 3(b) | For mixtures, composite goods and retail sets that 3(a) cannot resolve, classify by the material or component giving the essential character. |
| GIR 3(c) | If 3(a) and 3(b) fail, use the heading that occurs last in numerical order among those equally meriting consideration. |
| GIR 4 | Goods not classifiable under the rules above go to the heading for the goods to which they are most akin. |
| GIR 5 | Cases and containers specially shaped for an article, and packing materials normally used for the goods, classify with the goods; reusable packing is left to national discretion. |
| GIR 6 | Repeat the process at subheading level, comparing only subheadings at the same level and applying the Subheading Notes. |
By the end of GIR 5 all goods, with their containers, are classified to heading level; GIR 6 then selects the five- and six-digit subheading.
National extensions: from HS to HTS and Schedule B
Countries must keep every HS heading and subheading unchanged and may add digits for their own tariffs and statistics. Digits beyond the sixth are therefore national and differ between jurisdictions, so only the first six digits are comparable across countries. The United States tariff schedule is an example; see HTS lookup for searching it and HS code vs Schedule B for the export-side code. The special US provisions in Chapter 98 of the HTS are national. For chemicals, see HS code (chemicals). An HS code is also separate from an export-control classification such as an ECCN.
HS editions and HS 2028
The HS Committee prepares amendments every five to six years. WCO Trade Tools lists editions for 2002, 2007, 2012, 2017 and 2022. On 21 January 2026 the WCO announced the HS 2028 amendments: they enter into force on 1 January 2028, comprise 299 sets of amendments, and result in 1,229 headings and 5,852 subheadings. The WCO names public health, environment, enforcement and technology among the themes (WCO newsroom, 21 January 2026).
For researchers this matters because a code can be split, merged or moved between editions. When combining years of trade data, state the HS edition used and check a published correspondence table before joining series. Bilateral trade databases such as UN Comtrade report goods under HS editions, so the edition is part of the dataset’s identity.
How to cite the Harmonized System
Name the edition and the owner. A suggested APA 7 form for the nomenclature as a whole:
World Customs Organization. (2022). Harmonized System nomenclature, 2022 edition. https://www.wcoomd.org/en/topics/nomenclature/instrument-and-tools/hs-nomenclature-2022-edition/hs-nomenclature-2022-edition.aspx
In text, write the code with its edition: “potato starch (HS 2017, 1108.13)”. Report codes as text strings, not numbers, so leading zeros are not lost.
Extracting the six-digit HS prefix in Excel, R or Python
National codes often arrive with 8 or 10 digits, with or without dots. To compare across countries, strip dots and keep the first six characters. Treat the column as text.
Excel (code in A2): =LEFT(SUBSTITUTE(A2,".",""),6) gives 110813 for 1108.13.00.
R: substr(gsub("\.", "", "1108.13.00"), 1, 6) returns "110813". The chapter is substr(code, 1, 2).
Python: code.replace(".", "")[:6] returns '110813' for "1108.13.00"; [:2] gives the chapter and [:4] the heading.
Common mistakes
- Treating a ten-digit national code as an HS code; only the first six digits are harmonized.
- Classifying from the chapter title instead of the heading terms and Notes (GIR 1).
- Storing codes as numbers, which drops a leading zero (
0707.00becomes707). - Mixing HS editions in one time series without a correspondence table.
FAQ
What does HS stand for in HS codes?
Harmonized System, the WCO’s international nomenclature for classifying traded goods with a six-digit code.
How many digits does an HS code have?
Six internationally. Countries may add more digits for national tariffs and statistics.
Who maintains the Harmonized System?
The World Customs Organization, through its Harmonized System Committee, under the International Convention on the Harmonized Commodity Description and Coding System.
How often does the HS change?
Amendments are prepared every five to six years; the current edition is HS 2022 and HS 2028 enters into force on 1 January 2028.
Is an HS code the same as an HTS code?
No. The US HTS begins with the six-digit HS code and adds national digits. See HS code vs Schedule B.
Sources
- World Customs Organization, “What is the Harmonized System” (read 2026-11-11).
- World Customs Organization, Harmonized System: 30 Years On (compendium PDF, read 2026-11-11).
- World Customs Organization, HS Nomenclature 2022 edition page (read 2026-11-11).
- World Customs Organization, “HS 2028 amendments”, newsroom, 21 January 2026 (read 2026-11-11).
- WCO Trade Tools, Harmonized System edition list (read 2026-11-11).
