Current Government Statistical Service (GSS) Harmonisation team workplan

Current harmonised standard

The current harmonised standard for ethnicity is based on the questions used in UK censuses in 2011.

The recommendation is that people choose their own answer to the question about their ethnic group. This is because ethnicity will mean something different to each person.

It is also recommended that this standard is used together with the religion harmonised standard and national identity harmonised standard. The questions should be asked in the following order: national identity, ethnic group, religion.

For the censuses in England and Wales 2021 and Scotland in 2022, the current harmonised standard was reviewed and adapted. This was because of changes in respondent needs. The census questions were produced by balancing the new respondent needs with the need for coherence and comparability.

Because of this comprehensive work, if you are planning to include a new ethnicity question in your data collection and cannot wait for the review work to be completed, the questions in the censuses in England and Wales 2021 and Scotland in 2022 are recommended for data collection for ethnic groups at present. We recognise however, that user and respondent needs may have changed since the census questions were developed.

Progress since 2022

We began work to update the ethnic group harmonised standard following the publication of our initial workplan in 2022. Ethnicity was prioritised in 2022 due to:

• definitions, terminology, and thinking on the topic changing and developing
• events such as the Black Lives Matter movement and COVID-19 pandemic, which have demonstrated the need for more granular ethnic group data
• harmonisation’s response to the Inclusive Data Task Force’s recommendations to ensure the ethnicity standard reflects the diversity of the UK population

The broad aim of the work is to improve the inclusivity of the question for minority ethnic groups. We are developing the new ethnicity harmonised standard through the Agile stages of Discovery, Alpha, Beta, and Live. We are also using Respondent Centred Design and have adopted its most comprehensive, or  ‘gold’ level for the GSS harmonised standard ethnicity question design. We finished the research and early engagement work and published the findings from phase 1 and phase 2 of the Discovery phase in 2023. These reports outline the issues discovered with the current question, as well as data user needs.

In June 2025, we published an overview of our redesign research to date, outlining our emerging approach to a more inclusive and flexible ethnicity harmonised standard. Informed by extensive engagement and testing across the UK, the proposed changes, such as multiselect functionality, aim to better reflect how people self-identify. We are committing to maintaining alignment with the five high-level census categories to support data comparability.

In September 2025, we published findings from a review of ‘write-in’ responses from a range of UK sources. This work built on the methods outlined in our December 2024 publication, ”additional work to explore potential new response options“. The research presented in these two publications shows how we are exploring user needs for expanded response options for the new standard. Findings from the write-in response review will be considered alongside evidence gathered through public consultation later in 2025.  

The Ethnicity harmonisation standard consultation: assessing user needs for additional response options opened in October 2025 and closed in February 2026. It asked whether further tick-box response options may be needed in a future ethnicity harmonised standard and, if so, which options should be added. This consultation coincided with the Census 2031 Topic Consultations to maximise visibility to respondents.

In March 2026, we published the evaluation criteria being used to assess the consultation responses for requests for additional response options in the new ethnicity harmonised standard. This outlines how evidence from the consultation would be considered, including the framework for assessing user need, potential proxy data, public acceptability and prioritisation of any additional ethnic groups. Once the evaluation is complete, findings from the consultation will be reviewed alongside findings from the write-in response review. Together, these workstreams will inform the additional tick-box response options for the new standard.

In April 2026, we published an update on the consultation. This summarised who responded, how we engaged with users during the consultation period, and the next steps for assessing evidence and developing the new ethnicity harmonised standard.

In October 2026, we published the “We Asked You Said We Did” update for the consultation on the ONS Consultations website. This report outlines the requested ethnic groups that will proceed to the next stage of evaluation. We also published all responses to the consultation on the Analysis Function website.

The timeline for confirming new response options has lengthened because the volume of responses and the number of requested ethnic groups needing evaluation exceeded expectations. Taking more time will enable us to complete the evaluation thoroughly, including further research and engagement on public acceptability, so that any additional response options in the ethnicity harmonised standard are robust, evidence-based and clearly explained.

Priority activities

Priority activities for the next stage of work include:

• continuing alpha stage question design and testing for the new ethnicity harmonised standard
• completing the consultation evaluation of requested additional ethnic groups (Steps 3 and 4, described in the evaluation criteria publication)
• using consultation and write-in review findings to inform new tick-box response options

Timescale

We previously said that we expected to publish new response options in autumn 2026, with the final standard published by the end of 2026. We now expect to confirm any new response options in spring 2027.

In spring 2027, we will also publish the emerging standard, marking the end of the Alpha phase. The standard will then move into Beta for further testing at scale before it is finalised.

We expect to finish our research in line with the following timescales:

• confirming any new response options and publishing the end of Alpha emerging standard– spring 2027
• further testing of the proposed design in Beta before the standard is finalised
• designing and testing other data collection modes, including paper mode – following further Beta testing

We will provide a further Alpha research update before the end of 2026, setting out progress on question design and the remaining research needed to complete the Alpha phase.

Current harmonised standard

To collect data on disability in line with the Equality Act (2010) for Great Britain or the Disability Discrimination Act (1995) for Northern Ireland, the current recommendation is to use both of these standards together:

• long-lasting health conditions and illness harmonised standard
• activity restriction harmonised standard

Users can also collect data using the impairment harmonised standard. This will give more information about the things that people self-report they can or cannot do. These questions were developed before the UK censuses in 2011.

Progress since 2022

Work to update the disability and impairment harmonised standards began following the publication of the initial workplan in 2022. Since then, the Harmonisation team have published findings from their research and early engagement work. These reviews outline the strengths and weaknesses of the current standard, user needs for disability data and areas for potential improvement of the existing standards.

The findings from phase 1 of the research were published in March 2023.

The findings from phase 2 of the research were published in June 2025.

Latest update

Following the published recommendation on the future of population and migration statistics, including the recommendation for an England and Wales census in 2031, work on the disability and impairment harmonised standards is paused.

This will give the Harmonisation team space to consider all the current harmonised standards, prioritise updates across each topic, and communicate proposed standards for Census 2031.

Timescale

Updates on the status of the disability and impairment standards, and the work being undertaken by the Harmonisation team in light of the Census 2031 recommendation will be provided through the workplan, as they become available.

Current harmonised standards and guidance

Gender Identity

Our previous ‘under development’ gender identity harmonised standard, published in July 2020, was created using research and testing undertaken for Census 2021 in England and Wales. It was published as ‘under development’, acknowledging the need for further research to develop the standard. However, there are limitations to the data collected from this question. As of 12 September 2024, the gender identity estimates from Census 2021 are no longer accredited official statistics and are classified as official statistics in development. The ONS requested this change in designation after patterns were identified in the Census data that suggested that some respondents may not have interpreted the Census 2021 gender identity question as intended, notably those with lower levels of English language proficiency. In November 2023 an ONS report on the quality of Census 2021 gender identity data noted this bias, and analysis of Scotland’s 2022 Census trans status and history data has added weight to this observation. More information can be found in the final report on the quality of Census 2021 gender identity data, and in the National Statistical blog about the strengths and limitations of gender identity statistics.

Therefore, we have archived our gender identity data harmonised standard while we work to develop new harmonised standards for sex and gender identity. We have replaced the archived standard with new guidance for producers of statistics and researchers (December 2024) who are currently using, or thinking about including, a gender identity question on their surveys or in their administrative data collection.

Sex

The current harmonised standard for sex was published in October 2026, in which we prioritised the development for two target concepts of sex. These target concepts are aligned with different legislative instruments which have a bearing on an individual’s official records and status:

1. Biological sex (sex at birth) aligned with the definition for the purposes of the Equality Act, 2010,
   and
2. Certificated sex (sex at birth or as modified by a Gender Recognition Certificate) aligned with the legal recognition provided by the Gender Recognition Act, 2004

This reflects the urgent user need for statistical guidance shared with us by official statistics producers following the UK Supreme Court ruling. We recognise that user needs and the context for official data collection continues to evolve. Therefore, further testing may be needed to update the harmonised standard as circumstances change.

In April 2025, the UK Supreme Court ruled that sex, for the purposes of the Equality Act, refers to biological sex unmodified by a Gender Recognition Certificate (GRC). This means that sex-based protections under the Equality Act must be based on biological sex, that is, the sex of a person at birth. We use the term ‘certificated sex’ to mean a person’s sex at birth or as modified by a GRC.

Previously, there was no harmonised standard on the topic of sex. We have now archived our previous GSS Harmonisation page on sex, which provided summary information for statistical producers on the way sex has previously been collected in the UK’s censuses. As these questions and associated respondent guidance were designed before the April 2025 UK Supreme Court judgment on the meaning of sex for the purposes of the Equality Act 2010, we have archived this guidance and replaced it with the current harmonised standard for sex.

Progress since 2024

In December 2024 we launched a new phase of work towards agreed harmonised standards for sex and gender identity data collection. Harmonised standards allow people to effectively and accurately compare data that has been collected across different datasets. The harmonised standards we develop will consider both the collection of primary research data, and the secondary use of administrative-based data for research purposes.

Throughout this workplan, we are using the term “user” to refer to producers of statistics and data users. We are using the term “respondents” to refer to people who will be answering data collection questions and providing data during survey-based data collection, administrative-based data collection, or during testing research to develop harmonised standards.

We will be user and respondent-led on this work, and we will use the findings from each phase of user engagement and question testing to directly inform our subsequent work. Updates on our work will be published regularly throughout the development cycle.

Both agile methodology and the Respondent-Centred Design Framework emphasise the importance of gathering user needs early in project delivery, and using these needs to inform all subsequent work you undertake. By developing harmonised standards iteratively based on the needs of our users and the feedback we gather from respondents, we can ensure that the final harmonised standards are effective, evidence-based, and fit for purpose. Agile delivery consists of three main phases prior to going live; these are Discovery, Alpha, and Beta.

Discovery Phase

The Discovery Phase is about gathering insights from users and respondents about their needs. User needs refer to the requirements of statistical producers and data users. Respondent needs include usability, acceptability, and question comprehension.

During our Discovery Phase to date we have engaged with cross-government data collectors and producers of official statistics, to understand their needs for new harmonised standards. We also held a series of listening events across the UK in Spring 2025 to hear from data users, statistical producers and members of the public interested in data and statistics. As sex and gender identity data collection is important internationally, we have also engaged with international colleagues from National Statistical Offices to learn from their approach to sex and gender identity data collection.

We undertook a review of UK surveys collecting data on sex, gender identity or both, primarily identified through the most recent equalities data audit. The focus of this audit was government surveys, however some surveys conducted by non-government organisations were included. We also conducted a scoping review of UK academic literature covering sex and gender identity data collection and statistics.

We are currently analysing our findings from the qualitative research we conducted with respondents to understand how individuals with a range of backgrounds and perspectives conceptualise the topics of sex and gender identity. This means learning about what they draw upon to reach their understanding of different terminology and concepts, the thought processes that take place when surveyed, and how different questionnaire response options are understood. We will publish an update on phase 2 of our Discovery work in late 2026, and expect to commence respondent testing for gender identity questions at this time.

More information on our findings from this Discovery phase can be found in our published report.

Our workplan will continue to include research to explore user needs for, and respondents’ own interpretation of, terminology and questions on gender, trans status, and gender identity. Consequently, we anticipate a longer period of qualitative discovery work with users on these topics before progressing to Alpha. We will also continue to research other topics related to sex, such as variations in sex characteristics (VSC, sometimes referred to as intersex, or differences of sex development) during this time.

Alpha Phase

The Alpha phase is about using the insights gathered from Discovery research to make evidence-based decisions about question design. Question prototypes are designed, tested through research, refined based on research feedback, and then retested. This iterative improvement process continues until a final question design has been produced that is testing well and meets both users’ and respondents’ needs.

Our work with statistical producers and data users has found that there are clear priorities across the Government Statistical Service to be able to collect data aligned with the current legal positions, as set out in the Gender Recognition Act 2004 and the 2025 Supreme Court ruling on the definition of sex for the Equality Act 2010.

Before conducting cogability testing with respondents, we carried out interviews which explored respondents’ interpretation of 4 different styles of questioning on sex. This work provided background context for the respondent behaviours we would observe when subsequently testing candidate sex questions, and informed the initial design of prototype questions we would take forward to test in Alpha.

As part of our work to develop a sex harmonised standard for these purposes, we conducted 2 iterations of ‘cogability’ testing. This involves pairing cognitive interviewing with usability testing and is in line with Respondent Design Principles. Respondents are presented with questions as part of a prototype online questionnaire and encouraged to follow a ‘think aloud’ approach as they read and respond to the questions. More information on our work in the Alpha phase for the respondent testing findings from our sex question development can be found in our published report.

Our respondent testing for questions on sex was accelerated to meet priority user needs. As a result of this accelerated timetable for respondent testing, there are smaller population groups within the UK which we were unable to bring into our research sample. We have identified the need for additional follow-on research among populations who may require variation in questions to support their understanding of the question target, such as individuals:

• with a low English language proficiency
• with learning difficulties
• with variations in sex characteristics (VSC, sometimes referred to as intersex, or differences of sex development), who may have corrected their birth certificate or be considering doing so
• who have migrated to the UK from countries without comparable birth registration and certification processes

Beta Phase

The Beta phase is about quantitatively testing the questions that have been developed, at scale. This gathers statistical survey data insights and the ability to evaluate the effectiveness of the question design.

The next phase of work reviewing data collection for sex would align to the Beta phase, where questions can be quantitatively tested at scale. We anticipate working with data collectors looking to adopt these questions to monitor their performance in different survey contexts.

For gender identity, our plans for this will be informed by work in previous phases. They will be developed as we learn more about the concepts in use and question iterations throughout the Alpha phase.

Priority activities

We will continue work to develop a new standard for gender identity, and we recognise that user needs and the context for official data collection on sex will continue to evolve. Our work with users, stakeholders and respondents will continue throughout our workplan, and our guidance on data collection on these topics may need to change further as circumstances change.

We will also continue further additional research as part of the Alpha Phase for sex question respondent testing with smaller population groups within the UK, which we were unable to involve in our current sample, due to the accelerated timetable of this work. We will also test for other data collection modes, such as face to face and telephone, in additional to online.

Our work to develop a harmonised standard for gender identity may also affect our future guidance on sex. For example, this may be affected if additional advice is needed for statistical producers intending to present both sex and gender identity questions in the same data collection instrument.

Timescales

We expect to carry out further discovery work exploring concepts of gender, trans status, and gender identity during 2026. We will commence respondent testing for gender identity questions following this work. We also expect to carry out further qualitative research and engagement with variations in sex characteristics (VSC, sometimes referred to as intersex, or differences of sex development) populations during this time.

Our prospective timelines for finishing qualitative research for the development of updated sex and gender identity harmonised standards are as follows:

• Summer 2027 – updated harmonised standard online self-completion mode for biological sex (sex at birth) and certificated sex (sex at birth or as modified by GRC) data collection, applicable for survey or administrative data collection, following further respondent testing with smaller population groups
• Spring 2027 – harmonised standard online self-completion mode for gender identity data collection, applicable for survey or administrative data collection

These standards will be published thereafter, pending quantitative review, relevant approval and sign-off.

Standards for other data collection modes will be designed after this.

If you are interested in being kept informed of our progress, or would like to contribute to any of the phases of work previously described, please contact Outreach.Engagement.comms@ons.gov.uk.