Assessment of criteria for moving to admin-based population estimates as official estimates of population, England and Wales: 2026

This article explains our decision to publish official mid-year population estimates (MYEs) using established population estimates methods, rather than the admin-based population estimates (ABPEs) method. The term "ABPE" is used to represent a method of producing annual population estimates by applying a statistical model to administrative data to produce population estimates. ABPEs are not being adopted as official estimates, but we will continue to improve our population estimates using administrative data.

In our Quarterly update on population and migration statistics: November 2025, we announced we would publish a progress update in spring 2026 on our development to using ABPEs. This article provides that update, setting out progress made since our last ABPE assessment in May 2025 and updating our Action plan in response to OSR assessment of ONS admin-based population estimates.

Both this assessment and our previous assessment respond to the criteria outlined in our Criteria for moving to ABPEs as official estimates of population article. This article also outlines how we will continue to assess future improvements to ensure our population estimates are of suitable quality.

As part of this review, we have also considered recent developments such as the UK Government commissioning the Office for National Statistics (ONS) to conduct a census of England and Wales in 2031 and ONS's prioritisation of core population and economic statistics.

A range of evidence was considered during the review including:

• user feedback

• published materials

• extensive interviews with methodological experts, data and production teams 

The aim was to remove assumptions about the best way to produce population estimates while we assess the ABPEs against the criteria.

The main conclusion from the review was that adopting wholesale methodological changes would not be a sustainable approach given the context and progress in some areas against the criteria. For example, there are unexplained differences between the Long-Term International Migration estimates and migration outputs from the Dynamic Population Model. We will therefore continue to publish our official annual population estimates using established methods, adopting a continuous improvement approach. We will refocus our efforts on improving the main inputs that underpin them.

Central to the review was evaluating the lessons learned from producing both ABPEs and MYEs. We identified improvements during the review such as incorporating consistent quality checks spanning across the data supply, processing, validation and for the outputs. We will update users on these improvements through our Mid-year population estimates QMI, which we will publish alongside the mid-2025 official population estimates.

The evidence demonstrated clear value in the administrative data sources and modelling approaches developed so far, however, the review found that we had not sufficiently met the criteria for adopting ABPEs as our official estimates of the population. Questions around the quality of our data feeds for the models have led to a refocus on improving our input data before we can understand and demonstrate the robustness of our statistical models.

In May 2025, we published our Assessment of criteria for moving to admin-based population estimates (ABPEs) as official estimates of population, England and Wales: 2025 article assessing the readiness of the ABPEs to become the official population estimates. We identified further work required to fully meet the Criteria for moving to admin-based population estimates as official estimates of population, particularly:

• meeting the priority needs of users

• confidence in data supply and quality

• coherence and comparability

• systems and resource

We committed to reviewing the assessment again in spring 2026, ahead of the next annual population estimates publication. We have now completed this assessment based on the completed and planned work. For many of the criteria we have either already met the criteria or have confidence in our ability to meet them. However, our latest assessment shows that our ABPEs will not meet all of the criteria to be published as official statistics in 2026, specifically in the areas listed previously.

We have made significant progress in the areas requiring work, including;

• improvements to the way we publish our estimates and supporting information and wider engagement with stakeholders enabling a better understanding of the ABPE methods and outputs (meeting priority needs of users)

• publishing a quality overview of the data sources used in mid-2024 ABPEs, providing descriptions of the strengths and limitations of all the individual administrative (admin) data sources used (confidence in data supply and quality)

• improvements to our understanding of the quality of the data sources used in the ABPEs and the quality of the ABPEs using comparisons with the mid-year estimates (MYEs) and local insight from selected local authorities (confidence in data supply and quality)

• publishing our Evaluating the accuracy of the admin-based population estimates for England and Wales methodology and our Admin-based population estimates, local authority case studies article that share our findings on the quality of the ABPEs (accuracy and reliability) 

However, there is still further work to do to meet the acceptance criteria, including;

• addressing concerns expressed by users on the ABPEs, and MYEs, appearing too low for younger working age populations, particularly for those areas with student, migrant and transient populations (meeting priority needs of users)

• full quality assurance of the Statistical Population Dataset (SPD) method and production process (confidence in data supply and quality)

• providing reassurance on the sustainable supply of high-quality administrative sources used in the production of the ABPEs and to a lesser extent, the MYEs (confidence in data supply and quality)

• understanding and addressing the reasons for differences between the migration components of change (international, internal, and cross-border) produced by the ABPEs and UK long-term international migration (LTIM) estimates, published in our Long-term international migration, provisional: year ending June 2024 bulletin (coherence and comparability)

• users understanding the implications of moving to a new method on their funding models, including the likely step change in the population estimates series (coherence and comparability)

• ensuring the systems and processes needed to carry out the methods are efficient and reliable, such as applying quality standards to statistical code and developing reproducible analytical pipelines (RAPs) (systems and resource)

For the latest updates on the remaining criteria, please see our previous Assessment of criteria for moving to admin-based population estimates (ABPEs) as official estimates of population, England and Wales: 2025 article. While these criteria were put in place specifically for ABPEs, we will use these findings to help prioritise our research on future improvements to the population estimates. Our understanding of the quality of the data sources highlights where our focus needs to be, in prioritising input data including local level internal and international migration estimates.

waitingIn January 2025 we published a Criteria for moving to admin-based population estimates (ABPEs) as official estimates of population designed to assess our readiness for moving to ABPEs as our official population estimates. These criteria were tested with central and local government users through focus groups.

Some of the acceptance criteria are ABPE specific and not all are directly applicable to the current official mid-year estimates. For example, the "clear path towards becoming accredited official statistics" criterion related only to ABPEs. Therefore, by moving to an incremental, continuous improvement approach, rather than a step change to a different method, we need to adapt our evaluation approach.

We will continue to use the themes underpinning the acceptance criteria alongside a series of goals and objectives to assess any future improvements to our population estimates. We will develop these in a similar way to those described in the Census 2031 Strategy for England and Wales. Moving towards a more holistic approach of assessment will allow us to assess different methods in a consistent way.

The themes from the acceptance criteria we will use to assess our population estimates are:

• meeting the priority needs of users

• sound methods

• confidence in data supply and quality

• assured quality

• coherent and comparable estimates

• robust systems and sustainable resource

We requested an assessment of our ABPEs for England and Wales against the Code of Practice for Statistics from the OSR, with a view to them becoming accredited official statistics. The OSR published phase one of its review of admin-based population estimates for England and Wales in July 2024. The OSR also published The assessment of the Office for National Statistics' Admin Based Population Estimates: Independent expertise, which it commissioned from Professor Arkadiusz Wiśniowski, University of Manchester. We published our initial Action plan in response to OSR assessment of ONS admin-based population estimates in October 2024.

In parallel, the OSR is reviewing our current official mid-year estimates (MYEs) to ensure they still meet the requirements of the Code of Practice for Statistics. We expect to hear feedback in the coming months.

By adopting a continuous improvement approach, we will continue to develop our methods, while refocusing our efforts on improving the main inputs that underpin mid-year population estimates.

We will look to consolidate our approach of OSR assessments across the current methodology (MYEs) and the ABPEs focusing on the improvements we make to our established methods. This will ensure any future improvements to the population estimates adhere to the Code of Practice for Statistics. We will continue to work with OSR to ensure we produce the highest quality population estimates, some aspects of which will refer to recommendations in the OSR review of ABPEs. Our action plan will aim to address any recommendations from the OSR on the MYEs compliance check and the ABPEs phase one assessment, where it is reasonable to do so. Additionally, we will continue our work to meet the standards for accreditation for our international migration estimates, ensuring we are ready to seek this accreditation from OSR.

We will provide updates on any methodological changes ahead of the population estimates publishing in summer 2026. We will update users on our refreshed goals and objectives for population estimates as we develop these over the coming months.

We plan to review any outstanding recommendations and update our OSR action plans for population and migration estimates in our quarterly updates. We will continue to keep our users and OSR updated, sharing evidence of the improvements we are making.

Further information on our progress and plans for the year ahead can be found in our Quarterly update on population and migration statistics: March 2026 article.