The “Nomenclature of Statistical Territorial Units (NUTS)” (later called “Nomenclature of Territorial Units for Statistics”) was introduced by the Statistical Office of the European Communities (Eurostat) in the early 70s, in an agreement between other departments of then Commission of the European Communities and between the Member States of the European Economic Community (EEC). This agreement was aimed to establishing a single, coherent system of dividing the territories of the EEC Member States in order to generate regional statistics for the Community, which allow for a comprehensive overview of the changes taking place at a regional level in Europe. Over the years the implementation and updating of the NUTS classification was carried out as a part of a series of “gentlemen's agreements” between the Member States and Eurostat. There were six levels of then NUTS nomenclature: NUTS level 0 covering the whole country, three next levels defined as regional (i.e. NUTS level 1, NUTS level 2, and NUTS level 3) and the last two levels defined as local (NUTS level 4 and NUTS level 5). The NUTS classification has been used in Community legislation since 1988, when it was included in the Council Regulation on the Structural Funds^[1].

The work on granting the legal status to the NUTS classification began in 2000. It was completed in 2003 by the adoption of Regulation (EC) No 1059/2003 of the European Parliament and of the Council of 26 May 2003 on the establishment of a common classification of territorial units for statistics (NUTS)^[2]. At that time the uniform division of 15 Member States into NUTS units of three regional levels (NUTS level 1, NUTS level 2, and NUTS level 3) was established. These units were listed in Annex I of the Regulation, as following: 72 units of NUTS level 1, 213 units of NUTS level 2, and 1091 units of NUTS level 3. Pre-existing entities NUTS of level 4 and level 5 were defined as “Local Administrative Units”: LAU 1 and LAU 2 respectively. Although they are not specifically set by the Regulation, they were listed in its Annex III (at the LAU 2 level)^[3]. The Regulation also formally changed the name of NUTS territorial division from the “Nomenclature of Territorial Units for Statistics” into “Classification of Territorial Units for Statistics”. However, Eurostat widely uses the former name of the territorial division.

The NUTS classification established in 2003 (so-called NUTS 2003) is amended by revisions that may occur no more frequently than every three years:

• The first revision (NUTS 2006) was adopted on 1 February 2007 and entered into force on 1 January 2008^[4].
• The second revision (NUTS 2010) was adopted on 17 January 2011 and entered into force on 1 January 2012^[5].
• The third revision (NUTS 2013) was adopted on 9 December 2013 and entered into force on 1 January 2015^[6].
• The fourth revision (NUTS 2016) was adopted on 21 November 2016 and entered into force on 1 January 2018^[7].
• The fifth revision (NUTS 2021) was adopted on 24 October 2019 and entered into force on 1 January 2021^[8].

In addition, changes in the NUTS classification may occur as a result of the accession of new member states to the European Union or as a result of a significant reorganization of administrative division in the Member States. However, the changes made under this procedure are not considered as a new revision of the NUTS classification. They are regarded as a update of the current classification. So far, three changes have been implemented in accordance with this procedure:

• The NUTS classification was introduced for the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia, following their accession to the European Union in 2004^[9] (the classification formally has been in force since 26 November 2005, de facto it has been used since the accession of these countries to the European Union on 1 May 2004).
• The introduction of the NUTS classification for Bulgaria and Romania following their accession to the European Union in 2008^[10] (the classification formally has been in force since 6 March 2008, de facto it has been applied since 1 January 2008).
• The change of NUTS level 3 for Portugal after reorganization of its administrative division^[11] (formally has been in force since 1 January 2016, but according to the operating agreement with the Portuguese statistical office, it has been applied since 1 January 2015).

In addition, as a result of the withdrawal of the United Kingdom from the European Union on 1 February 2020, the division of this country into statistical units ceased to be a part of the NUTS classification.

The country in which the changes to the NUTS classification have been introduced is required to make, within two years, recalculations of the selected statistical data for the previous years in the revised NUTS level. A separate Commission Regulation determines required starting years for the time series by statistical domain for the new regional breakdown.