The future of census and population statistics in Northern Ireland: NISRA Recommendation

Published June 2025

Executive Summary

This paper outlines the Northern Ireland Statistics and Research Agency’s (NISRA’s) strategic vision for the future of census and population statistics for Northern Ireland. The recommendations we are putting forward are grounded in the successes of Census 2021, reflecting the evolving challenges in data collection, and evaluating the growing potential of administrative data to enhance statistical outputs.

The census is the single largest, most prominent and most complex statistical exercise undertaken by government. Usually held once every decade, the information it collects provides a rich and detailed picture of the population and society of Northern Ireland, covering every individual and every household at a specific point in time. The comprehensive nature of the census makes it crucial in a wide range of different settings. It helps to inform planning for public services; to ensure fair financial allocations; enables equality monitoring and a wide range of government and academic research.

The 2021 Census in Northern Ireland, conducted in partnership with the Office for National Statistics (ONS), achieved a record household response rate of 97% and marked a significant shift toward digital-first data collection, with over 80% of returns submitted online. Innovations in its approach included the use of digital technology to support the data collection, and an increased integration of administrative data to support operations. In addition, for the first time ever, digital dissemination was prioritised with the launch of user-friendly and accessible products such as the Census Area Explorer and the Flexible Table Builder.

Despite these successes, traditional survey methods such as the census face increasing challenges, brought about by:

  • Declining response rates to household surveys.
  • Societal changes, including an ageing and more mobile population, increased migration, and more diverse and complex household structures.
  • Rising demand for timely, granular, and high-quality statistics to support public services, equality monitoring, funding allocation, and research.
  • Increased costs of data collection exercises which are pressurising statistical agencies to find more efficient ways to gather data, while reducing respondent burden.

Administrative data, routinely collected by public and private bodies, offers a scalable, cost-effective complement to traditional surveys. While it lacks some contextual depth, its continuous nature supports real-time analysis and operational efficiency. In recognition of this NISRA, like its counterparts in the UK and internationally, has increasingly integrated administrative data into census operations such as: address register construction; targeting enumeration; supplementing data processing; and assisting with quality assurance and accuracy measurements.

NISRA believes that administrative data can be an important complement to a future census. There are significant and varied user needs in Northern Ireland for the type of detailed and granular information that only a census can provide, such as data on religion, ethnicity, national identity and language to support equality monitoring. Administrative data can be used to support this large scale data collection exercise to meet growing user needs and to make the collection as cost effective as possible.

NISRA is therefore making two key recommendations:

  1. NISRA should be commissioned to conduct a full Census of Population and Housing for Northern Ireland in 2031, which is transformative in its use of administrative data to maximise quality, efficiency, and public value – ensuring statistics about our population remain fit for our changing society.

    A Northern Ireland census in 2031 should be mainly online and build on the successes and innovations of Census 2021. It should be supported by technology and administrative data where relevant to maximise the value of the census and to keep respondent burden low.

  2. The Government provides its full support to NISRA in facilitating safe access to the necessary administrative data required to underpin the successful design and implementation of a census in 2031.

    In order to be effective, this support should include cross-departmental and UK Government cooperation to ensure that priority information needs are realised. Enabling NISRA to access and integrate relevant data sources will significantly enhance the value of the census, optimise user benefit and ensure the resulting insights are fit for incoming evidence-based policy and public service delivery.

Subject to approval, NISRA will plan for a 2031 Census which is guided by the following strategic objectives:

  • Public consultation: A major part of the planning for a census is consulting and engaging with stakeholders (including the public and users of census data). A Northern Ireland census in 2031 should be underpinned by a comprehensive assessment of future user need. As such, NISRA will run a public consultation on Census User Needs in Autumn 2025 to help NISRA understand what users’ future needs are for census statistics.

  • Design principles: NISRA will focus on building on the successes of the 2021 Census – focussing on providing high quality, value-for-money, fit-for-purpose statistics that meet user needs. This overarching aim will incorporate UK comparability, digital innovation and maximising the use of administrative data to support inclusivity, accuracy, enhancing data quality, building public trust and cost saving.

  • Continued collaboration: NISRA will work with the National Records of Scotland (NRS) and ONS to design and build censuses across the UK which are harmonised and coherent where possible. Alongside this, NISRA will continue to engage with the Central Statistics Office (CSO) and other international colleagues to continuously explore developments in technology, methods and approaches to support census planning and delivery.

  • Transparent reporting and accountability: NISRA will keep stakeholders and users informed of developments in the design and planning of a census in 2031 through a proactive, multi-channel communication strategy that prioritises transparency, clarity and engagement.

As the operational design details of a census in 2031 have not been decided, there is considerable financial uncertainty about the likely cost. That said, NISRA’s successful 2021 Census – delivered in partnership with ONS – created significant cost savings, arising from shared project management, procurement, contract management, communications and advertising functions. It is anticipated that any future joint project would be similar in its approach.

1 Introduction

This recommendation paper provides an overview of the Northern Ireland Statistics and Research Agency’s (NISRA’s) vision for the future of census and population statistics.

The census is the single largest, most prominent and most complex statistical exercise undertaken by government. Usually held once every decade, the information it collects provides a rich and detailed picture of the population and society of Northern Ireland, covering every individual and every household at a specific point in time. The comprehensive nature of the census makes it crucial in a wide range of different settings. It helps to inform planning for public services and to ensure fair financial allocations; it enables equality monitoring and a wide range of government and academic research.

Historically censuses have taken place in Northern Ireland at the same time as the rest of the UK, at ten yearly intervals1. The most recent census in Northern Ireland took place in March 2021, at the same time as the England and Wales census, in partnership with the Office for National Statistics (ONS). Working with ONS on Census 2021 provided considerable cost savings for Northern Ireland, arising from shared project management, procurement, contract management, communications and advertising functions. The 2021 Census was very successful, evidenced by a record high response rate of 97% and the very high uptake of online returns.

1 There are two exceptions to this – an additional mid-term census was taken across the whole of the UK in 1966, while Scotland moved their most recent census to 2022, due to the COVID-19 pandemic.

1.1 Successes of Census 2021

Although every census has unique features – reflecting new developments in technology, methodologies and evolving socio-demographic and economic circumstances – the success of Census 2021 makes it a rich study in data collection.

Census 2021 was the first census here that actively encouraged the public to complete their census online – with over 80% of households opting to return their questionnaires via this method.

Technology and new methods also played a pivotal role in how our outputs were generated and disseminated. Since May 2022, NISRA has produced a steady flow of Census 2021 analysis and products. A wide range of information in a variety of formats is now available through the NISRA website, and a dedicated Census Area Explorer enables users to access information about their local area in a user-friendly, digital manner.

For the first time ever for a census in Northern Ireland, census data was also made available online for users to access securely and independently via the Census 2021 Flexible Table Builder. This innovation was a step-change in the way census information was made available to the public, allowing them to query the census database flexibly and to undertake their own customised analysis, with disclosure control built in at the point of access.

Innovations in the way that data were disseminated were matched by innovations in data collection and processing activities. For Census 2021, the census fieldwork was supported by the provision of handheld devices to field staff with a fully integrated workflow system – greatly reducing the need for paper and allowing better management of workloads when following up with non-responding households.

Census 2021 also made much more use of administrative data sources to support data collection. These were successful in improving efficiency and inclusiveness by facilitating targeted enumeration and communication: for instance, data about limited access to broadband in certain areas allowed NISRA to prioritise the delivery of paper questionnaires to some respondents. These administrative data sources also supported post-collection processes such as consolidation of responses, de-duplication, coverage assessment and adjustment, and quality management.

Ultimately, however, the success of a census depends most heavily on the engagement of the public and the level of response. Census 2021 achieved an overall household response rate of 97%, which compares very favourably to 94% a decade earlier.

Conducted against the background of a global pandemic – with all its challenges and restrictions – and at a time when response rates for surveys have fallen internationally, this is a remarkable outcome which likely sets a historic benchmark in census taking here.

2 Challenges associated with data capture exercises

The demand for official population and social statistics has never been greater. Governments, businesses and third sector organisations are increasingly seeking to navigate rapid economic, social and environmental change, and depend on high-quality, timely and comprehensive data to inform their work. Data collection institutions such as NISRA are working to meet this need: collecting data which can provide insightful analysis in the most efficient, accurate and cost-effective ways possible.

2.1 Changing society

Over the last two decades, there have been significant changes in society. Some changes in the makeup of society have continued long term trends, having been evident in Census 2011, and continuing through into Census 2021. They include:

  • an ageing population;
  • a population with more complex living arrangements;
  • a more diverse population;
  • greater population mobility; and
  • greater numbers of single-person households.

These societal changes have presented new challenges for Government as they strive to meet the many and varied needs of the population. They also make gathering accurate, comprehensive data which captures the experiences of individuals and households more difficult.

2.2 Falling response rates to surveys

The Office for Statistics Regulation report on the State of the statistical system 2023/2024 published in July 2024, stated:

‘In the UK, and in other countries across the world, we have seen a steady decline in response rates to household surveys, which can reduce the accuracy of estimates and is a potential cause of bias in the survey data. Surveys will remain essential in some areas, but it has become more challenging and expensive to maintain quality.’


Traditional methods of data collection, such as door-to-door interviews, have faced particular challenges in recent decades. Response rates to these type of surveys have fallen in recent years (for example, target face-to-face response rates are now around 50%, while 10 years ago they would have been 60-65%), partly reflecting changes in labour market participation rates and wider social changes. As fewer individuals participate in surveys, the reliability of the insights and inferences that can be drawn from them falls, and they become much more costly to implement.

These trends – as well as the growth of digital capability and limited fiscal headroom – are driving data collection institutions to innovate and to find new, lower cost, more effective ways of reaching respondents. Well-designed surveys that embrace developments in digital tools and methodologies offer ways to reach wider and more varied audiences. These new methods can enhance the depth and breadth of insights – supporting evidence-based decision making by providing more detailed and targeted information that helps shape policies and services. As a consequence, household surveys remain a powerful tool for generating valuable insights about the population, their opinions and experiences, and emerging societal trends.

The high response rate to Census 2021 contrasted with the decline in response rates to other household surveys. This likely reflects the success of our digital-first strategy and the legal responsibility on citizens to complete the census. It is also likely that the COVID-19 pandemic had an impact on response rates, as a higher proportion of people were at home during the data collection phase.

2.3 The increasing use of administrative data

The growing availability of administrative data has transformed how data is used for policy making, research and service delivery – and has presented opportunities to address some of the issues associated with declining response rates to household surveys.

The strengths of administrative data make it a particularly effective complement to large scale survey and census data collections. Administrative data is typically updated continuously (or at regular intervals) and often covers a very large proportion of the relevant population. This makes it a rich source for timely analysis and decision making (for example, during the COVID-19 pandemic, the UK government used linked data to allow real-time monitoring of vaccine uptake). However, most administrative datasets lack important contextual or subjective insights (such as behaviours or attitudes) that are gleaned from survey responses. These sources are also often more limited in the availability of granular socio-demographic information that can be captured in tailored surveys.

An approach where administrative data is combined with survey data can bring the scale, frequency and continuity offered by administrative data, with the scope, flexibility and depth that survey data can bring.

In keeping with this theme, the United Nations has stated that it expects the 2030 census round will make much greater use of administrative data sources, both as a data source and to support field-based operations. Across the world national statistical institutes are exploring the use of administrative data as part of their strategy to address challenges around costs, quality, coverage and data availability. Many of these countries rely on the strength generated in combined methods. Countries such as New Zealand, Canada and Australia are actively looking at census alternatives. Indeed, a number of countries which previously surveyed the whole population are now using an administrative data-based approach. For example, the Netherlands, Austria, Switzerland and Singapore have fully or partly replaced their full census with an administrative data and survey approach.

Other countries have considered alternative reforms. France now runs a rolling survey which covers the majority of the population over a five-year time-window. The United States has also undergone significant reform shortening the length of their census questionnaire (for example the 2020 Census was only 9 questions in length), and meeting the demand for other population and social statistics with an annual compulsory survey – the American Community Survey (ACS). The ACS is a wide-ranging complex survey that gathers significantly more information than the Northern Ireland census, for example income data.

In Ireland, the Central Statistics Office (CSO) currently conducts censuses every five years, and recently has used administrative data to support their census in many ways, including:

  • Identifying signs-of-life in administrative or utilities data to determine the likelihood of household vacancy.
  • Addressing full and partial non-response. The census count covers all dwellings which were occupied in Ireland on Census night. Approximately 96% of the population completed a census form in 2022. Data for the remaining 4% of the population were sourced from alternative data sources, primarily administrative data.
  • Dropping questions on the census form and using administrative data (e.g. in Census 2022 CSO did not include a question on “field of study”, opting to use data from the education authorities).
  • Adding value to census outputs using admin data. The CSO matched household income to census micro-data to produce a new frontier statistical product on geographical profiles of income.

In addition, CSO has recently progressed considerable work on using administrative data in demographic estimation. This has mainly been driven by a new EU Regulation, European Statistics on Populations (ESOP), which is expected to come into force in 2028. It will present the CSO with considerable challenges to create more frequent and granular statistics, as the level of data required is similar to that collected through the census. In response to this, CSO has been developing new approaches to population estimates, in particular the Irish Population Estimates from Administrative Data Sources (IPEADS). This signs of life based methodology is expected to form the basis of meeting annual ESOP requirements.

3 Administrative data use in UK censuses

The use of administrative data to support a census is not new in the UK context. Across the jurisdictions, these data have been used to varying degrees in recent censuses to support operations, assist with data processing and the quality assurance of outputs.

3.1 Northern Ireland

In Northern Ireland, NISRA built on its experience of using administrative data to support Census 2011, by making greater use than ever before of the data collected by public and some private organisations to support Census 2021. For instance, administrative data were used to support Census 2021 in:

  • constructing and quality assuring the Census 2021 Address Register;
  • supporting the census field operation and ensuring the right approaches and resources were in place to maximise response;
  • data processing to cleanse the data, remove duplicates and fill any gaps in an efficient and accurate way;
  • estimating under-coverage and adjusting the census dataset to recover from non-response; and
  • quality assuring the census results – including comparing census data against a variety of statistical and administrative datasets to benchmark against independent sources, both at the national level and local level geographies.

Further details on how administrative data was used for Census 2021 are available in the information and methodology papers on the NISRA website and the Census 2021 General Report.

3.2 England, Wales and Scotland

In England, Wales and Scotland the ONS and NRS used administrative data sources to support their respective censuses in similar ways to Northern Ireland. As was the case for Northern Ireland, both jurisdictions utilised administrative data in the development and quality assurance of their respective address frames (the list of residential addresses used to contact people to take part in the census), and to quality assure the census results.

The ONS also mirrored NISRA’s approach to supporting the data collection exercise by using administrative data to predict how and when households were likely to respond, to ensure the right resources were in place to support those who needed help.

NRS applied administrative data in their data processing activities in a similar way to NISRA, but also had some specific applications, such as supplementing their post collection coverage survey with administrative data to reduce the uncertainty in their population estimates.

Full details of the data used and the approaches taken for England and Wales can be found in Administrative data used in Census 2021, England and Wales. Further details on Scotland’s use of administrative data in their 2022 Census are available in Scotland’s Census 2022 – General Report.

3.3 Looking to the future

An Independent report on the 2025 UK Statistics Assembly recognised that administrative data have considerable potential, but also limitations. One of the high level priorities suggested for the UK Statistics Authority and Government Statistical Service going forward, was to: Commit to, invest in, and take a leadership position in a significant scaling up in the use of administrative data, as well as improvement of its quality and coherence, across the entire portfolio of sources of official statistics, including government departments and external bodies, alongside and integrated with surveys, censuses, and other types of data.

Following Census 2021, efforts have been made to research the feasibility of expanding the use of administrative data further to attempt to produce census-type statistics from them – in keeping with developments internationally. In particular the ONS stepped up its efforts to mature this research, which led to a public consultation in England and Wales in 2023.

Since then, NISRA has worked closely with the ONS to understand the impacts of such work, with a view to understanding the opportunities for the production of census-type statistics from administrative data in Northern Ireland, and the potential impacts on the coherence of UK statistics.

The success of such an approach relies heavily on the availability of administrative data for statistical purposes. The joint work across the UK identified a number of data priorities which were common across the jurisdictions, but also highlighted that access to the relevant administrative records in ONS, NRS and NISRA was not equal.

Comprehensive UK-level data sources are particularly relevant to the production of census and population statistics. The more limited access to these data in Northern Ireland has presented significant challenges for NISRA – limiting its ability to apply them in a way that maximises their potential to support a census operation to the same degree that ONS can.

In addition, Northern Ireland’s data sharing legislation is not equivalent to that in England and Wales. In particular, the legal frameworks which surround access to health data differ: Northern Ireland does not currently have regulations which enable the sharing of secondary healthcare data for purposes other than the provision of care, which are present elsewhere in the UK. If NISRA is to be successful in its aspirations to make the next census operation as effective and efficient as possible, in the context of the data collection challenges outlined, it will require further support and investment in measures to increase the availability of data from these sources for statistical purposes.

4 NISRA Recommendation

In Northern Ireland, detailed statistics about our population, society and economy are essential for a wide range of purposes, such as:

  • Public service planning: Government departments and local councils use detailed data to allocate resources for healthcare, education, housing and transport – ensuring services are matched to population needs at local levels.
  • Equality monitoring: data on religion, ethnicity, national identity and language support equality monitoring under section 75 of the Northern Ireland Act 1998.
  • Funding allocation: population data underpins the distribution of UK funding streams to Northern Ireland, including those targeting rural development, deprivation, or peace-building initiatives.
  • Academic research and policy analysis: universities and academic research organisations use detailed and granular data to study demographic trends, migration patterns, social cohesion, and educational/economic outcomes across Northern Ireland.
  • Business and market planning: companies rely on detailed population statistics to identify opportunities, workforce availability, site locations etc across many sectors.

Both survey and administrative data face notable challenges. Surveys can be expensive and time-consuming to conduct and are increasingly impacted by declining response rates. By contrast, administrative data can have issues with coverage, consistency and definitions – and may be hard to access in the face of legal and technical barriers.

NISRA has considered the benefits and challenges of each and consider the best way to meet the needs of users in Northern Ireland, to be a combination of direct data collection through a census and linked administrative data. A census is required to capture the full range of information needed, particularly the need for information on specific population sub-groups and Section 75 characteristics. Administrative data can play a key supporting role in census operations, building on NISRA’s experience to date of integrating administrative data into recent censuses and seeking to link more data in a strategic way to make any future census operation as effective and efficient as possible.

NISRA has been actively engaged with ONS and NRS on the future provision of population data, collected to date through the Census of Population and Housing. The census recommendations for England, Wales and Scotland have also been published today, and closely reflect the route that NISRA considers would best meet the needs of users here. The level of harmonisation between each recommendation, significantly increases the potential for collaboration across jurisdictions – leading to enhanced opportunities for harmonisation and cost saving in the delivery of a census in 2031.

4.1 Recommendation 1

In view of these considerations, it is the recommendation of the Registrar General and Chief Executive of the Northern Ireland Statistics and Research Agency that:

NISRA should be commissioned to conduct a full Census of Population and Housing for Northern Ireland in 2031, which is transformative in its use of administrative data to maximise quality, efficiency, and public value – ensuring statistics about our population remain fit for our changing society.

A Northern Ireland census in 2031 should be mainly online and build on the successes and innovations of Census 2021. It should be supported by technology and administrative data where relevant to maximise the value of the census and to keep respondent burden low.

4.2 Recommendation 2

Given the increased reliance on administrative data to assist with a census in 2031, it is the recommendation of the Registrar General and Chief Executive of the Northern Ireland Statistics and Research Agency that:

The Government provides its full support to NISRA in facilitating safe access to the necessary administrative data required to underpin the successful design and implementation of a census in 2031.

A Northern Ireland census in 2031 should be supported by administrative data: to improve the coverage and cost effectiveness of census operations and respondent follow up; to check content and quality assure returns; to minimise respondent burden; and to increase the range of topics on which statistics are available.

In order to be effective, this support should include cross-departmental and UK Government cooperation to ensure that priority information needs are realised. Enabling NISRA to access and integrate relevant data sources will significantly enhance the value of the census, optimise user benefit and ensure the resulting insights are fit for informing evidence-based policy and public service delivery.

5 Next steps

Subject to approval, NISRA will plan for a 2031 Census which is guided by the following strategic objectives.

5.1 User needs consultation

A major part of the planning for a census is consulting and engaging with stakeholders (including the public and users of census data). A Northern Ireland Census in 2031 should be underpinned by a comprehensive assessment of future user need. NISRA will run a public consultation on Census User Needs in Autumn 2025. The consultation will be used to help NISRA understand what users’ future needs are from the census. Future need for census topics will feed into subsequent legislative proposals, and research priorities for content development, including questionnaire design and testing.

5.2 Census design principles

NISRA will plan for a 2031 Census which is guided by the following overarching design principles:

  • to build and innovate on the successes of Census 2021, extending the effectiveness of the online and digital collection process, while maximising opportunities to utilise technology for data processing and dissemination;
  • to maximise opportunities in the use of administrative data to support data collection, data processing and quality assurance – improving efficiency and maximising inclusiveness by using data to target small population groups;
  • to maximise overall response rates and minimise differences in response rates across all areas and among particular population groups;
  • to provide high quality, value-for-money, fit-for-purpose statistics that meet user needs, and which are consistent, comparable and accessible across the UK where possible;
  • to protect, and be seen to protect confidential personal information;
  • to secure public and user confidence in the final results and deliver them in a timely manner; and
  • to encourage wider use and exploration of census results to facilitate greater benefits from census outputs.

5.3 Legislation

The responsibility for making the necessary arrangements for planning, conducting and reporting on the census rests with the Registrar General for Northern Ireland. The statutory authority for taking a Census of Population and Housing in Northern Ireland is the Census Act (Northern Ireland) 1969. The Census Act gives the Registrar General for Northern Ireland powers for taking a census in any year that is at least five years from the year of the previous census.

Secondary legislation will also be required to enable a future census. For Census 2021, there was the Census Order (Northern Ireland) 2020 and Census Regulations (Northern Ireland) 2020. The date of the census and the content of the questionnaire is formally legislated for by the Assembly, with the topics to be covered being listed in a Schedule to The Census Order, and a copy of the final questionnaire is included as a Schedule to The Census Regulations, which enables a Census Order to be carried into effect and sets out, in detail, key elements of the census process.

The same process will be required for a census in 2031, with a similar timeline to that of the legislative process for the 2021 Census. In preparation for this, and following detailed consultation, development work and testing, NISRA will publish a Proposals Document in 2029 describing the planned census process from end-to-end. Alongside this, impact assessments on the requirements identified for each question and how NISRA will ensure that census data is kept secure will be published.

Separate legislation to enable data sharing between Departments and NISRA may also be required in future, to enable NISRA to access relevant and appropriate administrative data sources to support a census.

5.4 Funding

As the operational design details of a census in 2031 have not been decided, there is considerable financial uncertainty about the likely cost. NISRA’s successful 2021 Census – delivered in partnership with ONS – cost around £35m over a ten-year lifespan. Given the inflation which has been experienced since – and the dependence on IT services – our initial estimates of the cost of a 2031 Census range between £50m and £70m over a ten year period.

5.5 Collaboration

Today (17 June 2025), the three UK statistics organisations (NISRA, NRS and ONS) each published documents which include recommendations to conduct full censuses of population and housing within their own jurisdictions in 2031.

The UK Concordat on Statistics sets out how the UK and Devolved Governments cooperate in relation to the production of statistics, statistical standards and the statistics profession. If direction is given to conduct a census in 2031, NISRA will support the ambitions noted in the recent Independent Review of the UK Statistics Authority, by working with NRS and ONS to design and build censuses across the UK which are harmonised and coherent where possible.

The close partnerships that NISRA has had with ONS and NRS during the last three censuses has worked well and has contributed to significant cost savings for NISRA, arising from shared project management, procurement, contract management, communications and advertising functions.

Alongside this, NISRA will continue to engage with the Central Statistics Office (CSO) and other international colleagues to continuously explore developments in technology, methods and approaches to support census planning and delivery.

5.6 Reporting and accountability

NISRA will keep stakeholders and users informed of developments in implementation of these recommendations through a proactive, multi-channel communication strategy that prioritises transparency, clarity and engagement.

The NISRA website will be the main vehicle for this communication, but will also be supported by public consultations, webinars and community meetings.

6 Key statistics

Contact details

Northern Ireland Statistics and Research Agency
Colby House
Stranmillis Court
Belfast
BT9 5RR

Telephone: +44 (0)300 200 7836
Email: census@nisra.gov.uk
Web: www.nisra.gov.uk