The Census 2021 Data Asset (CDA) aims to be an anonymised record-level representation of the usually resident population, with scope to extend to a wider set of definitions in the future. Once developed, it will include demographics and characteristics such as age, sex, ethnic group, country of birth and nationality. It will be statistically controlled using weights from the Dynamic Population Model (DPM). That is, the population totals in the CDA will match those in the DPM by age, sex and local authority, ensuring coherence with published population totals. 

With the high-level design of the CDA set out, work towards the CDA is planned for later in 2023 and will begin with a proof of concept stage so that methods and processes can be developed and tested. This will demonstrate how the record-level population can be updated on an annual basis. Following this, we will seek to understand public acceptability of the CDA. ONS will engage with the public, through focus groups and community engagement, throughout the development of the CDA to ensure that it is developed and implemented for the public benefit. 

The CDA forms part of our population and social statistics transformation programme, which aims to provide the best insights on population, migration and society using a range of data sources. This work is part of the evidence base for the 2023 National Statistician's Recommendation on the future of population and social statistics.