Executive summary

Statistics about the population and migration are a vital input into decision-making by public, private, and voluntary sector bodies. They help people understand the evolving society that we live in. They help central and local government ensure that public services are delivered to the people who need them, and that resources are allocated effectively. They help businesses invest in the right places. And they help users of UK-wide statistics gain a coherent understanding of the population across the UK.

For decades, the Office for National Statistics has asked questions of the whole population through the decennial census for England and Wales. This has been pivotal in this system and has underpinned reliable and consistent measures of population and migration statistics.

The Authority’s vision is to deliver a sustainable population statistics system that generates high-quality, trustworthy data. Through consultation the ONS has found that users continue to find the decennial census an invaluable asset in meeting their needs. But they also told us they require more frequent and timely statistics to understand the changes that are occurring within society.

The Authority recommends that the Government commission a questionnaire-based census of the whole population in 2031. Delivering a census in 2031 is an exciting opportunity to build a system of population and migration statistics that combines the strengths of whole-population data collection with the additional value that administrative data can provide.

The ONS has decades of experience in delivering censuses. In 2031, the ONS would build on its experience from Census 2021, This was the first census to be completed primarily online, achieving a high response rate, and made greater use  of administrative data than its predecessors. In 2031 the ONS would look to broaden the use of administrative data to create further efficiencies and be more inclusive, in light of the progress it has made with administrative-based (‘admin-based’) statistics over the past decade and in line with changes seen internationally.

Our use of administrative data has developed considerably since 2021. While it is not yet mature enough to negate the need for a census, it can and should play an increasingly important role in the future system, supporting the Census and enabling more frequent, higher quality estimates on a broader range of topics before and after the census.

In the Beyond 2011 programme, ONS explored the ways in which population data are collected and since then, progress has been made in providing admin-based population and migration statistics.

This includes published in-development administrative-based population estimates for mid-2023 and our official estimates of long-term international migration, published in May 2025.

The safety of the public’s personal information is a top priority. The ONS has a strong track record of protecting sensitive data, underpinned by legislation and built over many decades of delivering the census in England and Wales and the UK’s biggest regular household surveys. The ONS’s recently updated Data Strategy reaffirms and updates its commitment to data protection and security. Published statistical outputs never identify individuals.

The Government has made a clear commitment to a transformative digital agenda as a significant driver of reform in public services. This is an important opportunity to drive the use and quality of administrative data – not just for population and migration statistics but more widely. These data hold the potential to deliver benefits across society through ONS statistics, while the necessary improvements to the quality of the underlying sources would also benefit supplier organisations, and help to measure progress with the Government’s five Missions and Plan for Change.

Several countries have mandatory population registers that help to improve the linkage of administrative data for the creation of statistics. International comparisons on this theme were made in the recent Independent Review of the UK Statistics Authority. This matter is beyond the remit of the Authority, but new Government initiatives relating to digital identification may provide similar statistical benefits and the ONS would seek to be a partner in their development.

The combination of a questionnaire-based census of the whole population with the effective use of administrative data would create a resilient and future-focussed population statistics system. This will help to provide users with the detail they require, while also providing an improved understanding of how society is changing in the years between censuses.

These recommendations would allow the ONS to maintain the pace and ambition of its work to embed administrative data in its population and migration statistics, while responding to user feedback for a comprehensive and inclusive data collection.

The ONS is responsible for carrying out the census in England and Wales, but the power to call a census rests with government ministers. Decisions on the future of the census in Scotland and Northern Ireland will be made by the relevant ministers, based on advice from their statistical authorities, in due course.

As highlighted in Professor Denise Lievesley’s recent Independent Review of the UK Statistics Authority, it is vital that the UK’s statisticians work together to ensure that coherent and comparable UK population data and statistics continue to be produced to inform communities across the UK. The Authority has published its 2024 report (English only) on this collaborative work to support UK coherence.