The Office for National Statistics (ONS) has been comparing census gender identity data with other available sources and examining what data patterns and other information collected on the census show about how people answered the question.   

We published our first research report, which examined whether the information that people provided on the census was coded and processed accurately, in June. This report, Collecting and processing Census 2021 data on gender identity, concluded that 94% of respondents to the census answered the voluntary question and there was no evidence to suggest that the published results were not coded or processed accurately.

Further, it reviewed the rigorous development and testing process the question went through. This involved trans and non-trans people and, through the 2019 Census Rehearsal, people who did not have English as their main language before the final wording was confirmed through legislation. Evaluation of the question during its development concluded that the final version met the requirements of public acceptability, being understood by respondents and providing the data needed by users.  

Broader user engagement exploring what would be helpful to users of census data on this question is continuing to ensure we are providing the right information for them to use census data in an informed way. This work includes building on the user requirements identified when deciding to recommend the inclusion of a question on this topic in the census and exploring how the data are being used.  

The users we have spoken to have made limited use of the census data on gender identity so far but would like to use data on this topic to help monitor performance against public sector equality duties and to better understand characteristics of the trans population. They told us that they expected higher levels of uncertainty for the census estimates for this topic as they are based on a voluntary question.  

The breadth of users for these data is wide and includes government departments, local authorities, private sector groups, charities and individual users including academics. Our next publication will reflect all of these interests.  

We have or are looking to speak to representatives of all these groups to inform our ongoing research and welcome other users of census gender identity data getting in touch with their needs by emailing    

We will publish further updates in due course.