Census of Ireland

• May 1813 (failed due to lack of returns and organisation)
• 1821 (failed due to lack of returns and organisation)
• 1831
• Sunday, 6 June 1841
• 1851
• 1861
• 1871
• 1881
• Sunday, 5 April 1891
• Sunday, 31 March 1901
• Sunday, 2 April 1911
• Sunday, 24 April 1921 (not taken due to Irish War of Independence)

All censuses were held on Sundays.

• 18 April 1926^[3]
• 26 April 1936
• 12 May 1946
• 8 April 1951
• 8 April 1956
• 9 April 1961
• 17 April 1966
• 18 April 1971
• 1 April 1979^[a][4]
• 5 April 1981
• 13 April 1986
• 21 April 1991
• 28 April 1996
• 28 April 2002^[b][5]
• 23 April 2006
• 10 April 2011
• 24 April 2016
• 3 April 2022^[c][6]
• 9 May 2027^[7]

Under Article 16 of the Constitution of Ireland, revisions of Dáil constituencies by the Oireachtas are required at a minimum every 12 years. However, they must also have due regard to changes in the population.^[8] Under the Electoral Reform Act 2022, the Electoral Commission is required to conduct a review of constituency boundaries after every census. From 1997 up to the establishment of the Electoral Commission in 2023, this function was carried out by a Constituency Commission created for this function.

From 1971 to 2006, census towns were "defined as a cluster of 50 or more occupied dwellings where, within a radius of 800 metres, there was a nucleus of 30 occupied dwellings". From 2016, a new census settlement was defined "as a minimum of 50 occupied dwellings, with a maximum distance between any dwelling and the building closest to it of 100 metres, accompanied by evidence of an urban centre". For the 2022 census, the CSO developed a new urban geography term the Built Up Area (BUA) to define urban areas.^[9]

Due to the explosion in the Public Record Office in Dublin during the Irish Civil War in 1922, the 1813–1851 censuses were destroyed except for a few enumerators books and transcribed records (which were recovered from the wreckage and donated). Furthermore, all censuses from 1861-1891 were deliberately destroyed, the 1861–1871 were destroyed for the protection of privacy. Furthermore, in 1918, due to a paper shortage, the 1881–1891 were pulped, against the request of the staff at the Public Record Office in Dublin.^[10]

There is an active attempt at recovering the 1813–1851 censuses and re-constructing them with the Virtual Record Treasury of Ireland. In July 2025, "over 200,000 names" were released by the Virtual Record Treasury in their new Knowledge Graph.^[11]

The 1901 and the 1911 Censuses were released in the 1961 by order of the Minister of Justice, Oscar Traynor to compensate the loss of earlier records.^[12] The data of the 1926 Irish Free State Census was released online on 18 April 2026, the centenary of the census.^[13] Later Censuses are not currently public due to Section 35 of the 1993 Statistics Act which bans the release of census return forms until 100 years after the enumeration date.^[14]