The 2021 UK Census was the 23rd official census of the United Kingdom. The UK Census is generally conducted once every 10 years, and the 2021 censuses of England, Wales, and Northern Ireland took place on 21 March 2021. In Scotland, the decision was made to move the census to March 2022 because of the impact of the coronavirus pandemic. The censuses were administered by the Office for National Statistics (ONS), the Northern Ireland Statistics and Research Agency (NISRA) and National Records of Scotland (NRS), respectively. In England and Wales, Census 2021 was the first census with a digital-first design, encouraging participants to respond online rather than on a paper questionnaire.Topics covered in the 2021 UK Census included:demography and migrationethnic group, national identity, language and religionlabour market and travel to workhousingeducationhealth, disability, and unpaid careWelsh and other languagesUK armed forces veteranssexual orientation and gender identity. Census flow data involve flows of individuals in the UK between origins and destinations. These flows are either the residential migrations of individuals from one place of usual residence to another, or of commuters making journeys from home to workplace or place of study. These data are derived from the questions on the census form relating to usual place of residence one year ago, and the place of work for the respondent's main job. Flow data are currently available at a range of different spatial scales ranging from Output Areas to Local Authority Districts. The Census Support: Flow Data website facilitates access to the interaction data for members of UK higher and further education institutions. Access is provided through the Web-based Interface to Census Interaction Data (WICID).Explicit registration is not required for the 2021 Census products that have been released under the Open Government Licence. However, outputs from the 2021 Census classified as 'Safeguarded' require users to agree on additional terms and conditions. Access to these datasets is only permitted via Federated Access. The Flow Data website provides two basic routes to the data.WICID is the main route to the flow data. It provides a flexible service to download extracts of data in a variety of forms;the Downloads page allows users to download the original tables as released by ONS and NISRA.Access data through the WICID Flow Data website. View the Census flow data guide.