Work on the introduction of the Nomenclature of Territorial Units for Statistical Purposes was associated with the negotiations on Poland accession to the European Union that started in March 1998. It resulted in the need to adjust Polish statistical division of the country for the rules established by Eurostat (i.e. the Classification of Territorial Units for Statistics – NUTS). This work was also associated with the introduction of the new administrative division of Poland on 1 January 1999. Powiats, as the second level of administrative division were restores. Moreover, the number of voivodships was reduced from 49 to 16. Until 31 December 1998 the statistical data was collected for the administrative division units (i.e. voivodships and gminas) as well as for macroregions grouping several voivodships (there were 10 such macroregions in 1998^[1]).

A new territorial division used for statistical purposes was developed under the new administrative division of Poland. This division was finally introduced by the Regulation of the Council of Ministers of 13 July 2000^[2] and entered into force on 8 August 2000. The entire state area was divided into five territorial levels – three higher levels were called as regional (NTS 1 – the whole country, NTS 2 – voivodships, NTS 3 – subregions grouping powiats) and two lower were defined as local levels (NTS 4 – powiats, NTS 5 – gminas with additional urban parts and rural parts of urban-rural gminas as well as districts and representations of selected cities). At that time 4076 NTS units were established: 1 unit at NTS 1 level, 16 units at NTS 2 level, 44 units at NTS 3 level, 373 units at NTS 4 level, and 3649 units at NTS 5 level (i.e. 2489 gminas, 567 urban parts of urban-rural gminas, 567 rural parts of urban-rural gminas, 7 districts of Warsaw, and 19 representations of four cities).

After the implementation, the Nomenclature of Territorial Units for Statistical Purposes was modified several times, usually once a year. These changes (such as: the addition or omission of units, the change of their names or codes) were mainly resulted from changes in the administrative division of Poland at powiat and gmina levels (including a granting town rights for localities, which resulted in a following change: a rural gmina became an urban-rural gmina and consequently it was represented by three units in the NTS classification – an urban part of gmina, a rural part gmina and a gmina as a whole):

• 1 January 2001 – 8 units of NTS 5 level were added (4 rural gminas were transformed into urban-rural gminas)^[3];
• 19 April 2002 – the division into NTS 3 subregions in Śląskie Voivodship was changed (1 subregion was added, boundaries of 3 subregions as well as names of 2 subregions were changed). Moreover, 7 units of NTS 4 level were added (newly established powiats), and names of 2 units of NTS 4 level and 13 units of NTS 5 level were changed^[4];
• 27 October 2002 – due to the modification of the administrative structure of Warsaw, several changes were introduced in NTS 5 level (1 gmina was abolished, 11 gminas were transformed into districts, 1 gmina was added) as well as a name of 1 powiat was changed^[5];
• 1 January 2003 – 1 unit of NTS 4 level was abolished (city with powiat status Wałbrzych) and 2 units of NTS 5 level were added (1 rural gmina was transformed into urban-rural gmina)^[6];
• 1 January 2004 – 4 units of NTS 5 level were added (2 rural gminas were transformed into urban-rural gminas) as well as names of 4 units of NTS 5 level were changed^[7];
• 1 May 2004 – NTS level 1, as the consequence of Poland accession to the European Union was amended. This level was renamed to “regions” (instead of one unit named “Polska”) and split into 6 units: region centralny, region południowy, region wschodni, region północno-zachodni, region południowo-zachodni, region północny^[8];
• 1 January 2005 – 2 units of NTS 5 level were added (1 rural gmina was transformed into urban-rural gmina) as well as a name of 1 unit of NTS 5 level was changed^[9];
• 1 January 2006 – 4 units of NTS 5 level were added (2 rural gminas were transformed into urban-rural gminas)^[10];
• 16 March 2006 – changes resulting from the transfer of one gmina between powiats were introduced^[11];
• 1 January 2007 – 4 units of NTS 5 level were added (2 rural gminas were transformed into urban-rural gminas)^[12];
• 1 January 2008 – new Regulation of the Council of Ministers on the establishment of the Nomenclature of Territorial Units for Statistical Purposes (NTS) entered into force. It changed the division of NTS 3 level: the number of subregions was increased from 45 to 66 (new subregions were introduced in 14 voivodships). In addition, 4 units of NTS 5 level were added (1 rural gmina was transformed into urban-rural gmina and 1 urban gmina was transformed into urban-rural gmina)^[13];
• 1 January 2009 – 10 units of NTS 5 level were added (5 rural gminas were transformed into urban-rural gminas)^[14];
• 1 January 2010 – 13 units of NTS 5 level were added (a newly established gmina and 6 rural gminas were transformed into urban-rural gminas) and names of 2 units of NTS 5 level were changed^[15];
• 1 January 2011 – 10 units of NTS 5 level were added (5 rural gminas were transformed into urban-rural gminas) and names of 2 units of NTS 5 level were changed^[16];
• 1 January 2013 – 1 unit of NTS 4 level was added (city with powiat status Wałbrzych) and name of 1 unit of NTS 5 level was changed^[17];
• 1 January 2014 – 12 units of NTS 5 level were added (5 rural gminas were transformed into urban-rural gminas and 1 urban gmina was transformed into urban-rural gmina)^[18];
• 1 January 2015 – the number of units of NTS 3 level was increased from 66 to 72 (new subregions were introduced in 4 voivodships: Kujawsko-Pomorskie, Małopolskie, Mazowieckie, and Pomorskie). Furthermore, boundaries of subregions in 2 voivodships were changed (Opolskie and Zachodniopomorskie). Moreover, 1 unit of NTS 5 level was abolished (gmina was attached to another one) and 6 units of NTS 5 level were added (2 rural gminas were transformed into urban-rural gminas and 1 urban gmina was transformed into urban-rural gmina)^[19];
• 1 January 2016 – 10 units of NTS 5 level were added (4 rural gminas were transformed into urban-rural gminas and 1 urban gmina was transformed into urban-rural gmina)^[20];
• 1 January 2017 – 10 units of NTS 5 level were added (4 rural gminas were transformed into urban-rural gminas and 1 urban gmina was transformed into urban-rural gmina)^[21].

Since Poland accession to the European Union, changes at regional level (NTS 1, NTS 2, NTS 3) may only occur in parallel with similar changes introduced by Commission Regulation (EU) amending the Classification of Territorial Units for Statistics (NUTS).

As a result of changes in the NUTS classification, introduced by the NUTS 2016 revision and being in force from 1 January 2018, the administrative division of the voivodship level has ceased to correspond to the statistical division at the NUTS 2 level. Consequently, it was not possible to apply the previous hierarchical scheme of merging administrative and statistical levels in one NTS Nomenclature. Therefore, it was decided to repeal the regulation of the Council of Ministers on the establishment of the Nomenclature of Territorial Units for Statistical Purposes. This repeal was also triggered by the fact that the NTS Nomenclature had been introduced when the NUTS Classification was not in force in Poland. After the introduction of the NUTS Classification, the NTS Nomenclature doubled both the NUTS regulations and the administrative division of the country. The Regulation of the Council of Ministers on the repeal of the Nomenclature of Territorial Units for Statistical Purposes (NTS) was published in the Journal of Laws on 24 April 2017^[22], and the NTS Nomenclature was abolished on 1 January 2018.

When the NTS Nomenclature was abolished (as of 31 December 2017), there were  4231 NTS units: 6 units at NTS 1 level, 16 units at NTS 2 level, 72 units at NTS 3 level, 380 units at NTS 4 level, and 3757 units at NTS 5 level (i.e. 2478 gminas, 621 urban parts of urban-rural gminas, 621 rural parts of urban-rural gminas, 18 districts of Warszawa, and 19 representations of four cities).

The division of Poland into NTS 1 units which was in force from 1 May 2004 to 31 December 2017

The division of Poland into NTS 2 units which was in force from 8 August 2000 to 31 December 2017

The division of Poland into NTS 3 units which was in force from 1 January 2015 to 31 December 2017
(the boundaries of voivodships and powiats are given as of 1 January 2015)