The Authority has recommended a statistical system for population and migration that combines data collection through a questionnaire-based census of the population with increased value from administrative data, but the decision to call a mandatory census lies with government ministers.

The ONS last carried out a census of England and Wales in 2021. Censuses in Scotland and Northern Ireland are carried out by National Records of Scotland (NRS) and Northern Ireland Statistics and Research Agency (NISRA) respectively.

There have been questions over the future of the census, centred on discussions on the possibility of producing population estimates based on alternative sources including administrative data, such as tax or benefit data. 

The decennial census began in England and Wales over 200 years ago, and has been carried out once every 10 years, with the exception of 1941.

The ONS held a public consultation on the future of population statistics in 2023. In a statement, the body said a ‘wide range’ of census users had expressed the value that the decennial census offers in bringing them the detail they need.

ONS received 706 responses to the consultation, with users asked why population statistics are important to them. One of the concerns raised during the consultation, according to the outcomes report, was over quality, with respondents noting that ONS would not have control over the administrative data collection process and subsequent data quality for administrative data sources collected by other government departments. 

The national statistician’s recommendation, endorsed by UKSA, is to commission a mandatory questionnaire-based census in 2031 and to continue to develop the ONS’s population and migration statistics based on administrative data to provide ‘more frequent and timely estimates'. The recommendation also urges the UK and Welsh governments to commit to a regular flow of administrative data to maintain and further improve estimates, which would leave open the possibility of moving to a system more fully reliant on administrative data in the future. 

If the government accepts UKSA’s recommendation, the ONS will develop plans for Census 2031, building on the last one in 2021 and starting with a public consultation later this autumn. The consultation will gather views on topics that census users need from a system of population statistics, drawing on both census data collection and use of anonymised administrative data.

Acting national statistician Emma Rourke said: “The ONS ran a highly successful census in 2021, at a pivotal time for the country. The high response rate and richness of the census data ensured it provided a high-quality snapshot of the whole population and its characteristics, which continues to provide benefits to statistical users.

“It has been clear from consultation and engagement that the decennial census, asked of the whole population, remains of enormous value for informing the most important decisions facing our country.”

She added: “In addition to a census data collection, we also know that there is strong interest in – and enthusiasm for – the improvements to quality, frequency and range of outputs we can see by making greater use of alternative data sources, especially administrative data. The progress we have made means we are well placed to use administrative data to contribute to our census activity and provide improved outputs between censuses.”

UK Statistics Authority chair Sir Robert Chote said: “The census has long been a vital tool for understanding our society and informing decisions by policymakers, public service providers, businesses and citizens.

“We believe that delivering a high-quality census for England and Wales in 2031 while further developing population estimates based on administrative data is the best way to serve the public good. Each will complement the other, strengthening our statistical system so that it is ready to adapt to the technological and social changes of the next decade.”

The ONS is responsible for the census in England and Wales. Decisions on the future of the census in Scotland and Northern Ireland will be made by the relevant ministers, based on advice from their statistical authorities.

In the foreword to the recommendation, Chote said: "We believe that this recommendation for England and Wales provides a constructive foundation for the equivalent decisions that will need to be taken in Scotland and Northern Ireland and would underpin sound UK-wide estimates."

Jane Frost, chief executive, MRS, said: “Researchers will breathe a collective sigh of relief this morning at the news that ONS – upon the government’s agreement – will hold a Census in 2031.  Our £9bn market and social research sector in the UK has long relied on the survey’s rich, consistent and reliable data to provide businesses and policy makers with all-important insight, informing critical decisions across public and private sectors. 

“As progress is made to improve the collection of this data and invest in alternative administrative sources, we’re keen to work with the government and ONS to put systems in place which will ensure the level of quality insights which the UK has enjoyed since the census’ conception.

“We are also calling for the ONS to work with us to develop refreshed methodology around the social grade for census data, reflecting the changing nuances of our society and social class.”