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The CSO Standard Country Classification is a classification of countries largely based on the ISO 3166 - codes for the representation of names of countries and their subdivisions.  The ISO 3166 is an international classification developed by the International Standards Organisation (ISO), and based on a listing of country categories maintained by the United Nations Statistics Division. It must be reviewed at no longer than 5-year intervals and updates are made available on the Internet. The ISO 3166 is available from the NSAI website.

In the CSO Standard Country Classification a country is defined as the current name, either short or official (as established by the International Standards Organisation), of a country or dependent territory. This includes:

  • independent countries recognised by the United Nations
  • administrative subdivisions of certain countries, in particular the United Kingdom
  • overseas dependencies, external territories of independent countries


This is a flat classification with a total of 258 categories, made up of 2, 4, 5 and 8-digit codes.

This Classification is based on the most recent version of ISO 3166 Country Codes and was previously reviewed and updated in 2021.  The 2022 review updated the codes for the constituent parts of the United Kingdom (England, Scotland, Wales and Northern Ireland) and included the addition of two Spanish enclaves - Ceuta and Melilla.  It also incorporates the revised spelling of Turkiye, which was implemented by the ISO in September 2022. This update caters for various survey needs within the CSO.

Further Information

Further information on this classification may be obtained from:

Classifications and Standards Section
Central Statistics Office