Methodological Assurance Review Panel Migration Statistics sub-group annual report: 2025 to 2026

The Migration Statistics subgroup continued with its membership unchanged. The subgroup is chaired by Professor Nik Lomax, with membership comprising Dr Marie McAuliffe, Professor Arkadiusz Wiśniowski, Professor Jakub Bijak and Georgina Sturge. It provides independent, expert technical assurance on the methodology used to produce international migration statistics.

Over the year, the subgroup advised on improvements to UK international migration statistics, with a focus on strengthening coherence, transparency and the use of administrative data. Two meetings were held. The first meeting held in October’25 was used to sign off methods that were subsequently implemented, which led to a longer gap while this research was operationalised and new areas of work were developed ahead of the next meeting in July‘26. Discussions covered developing methods and data sources, including visa and non-visa overstayers, work-related visa cohorts, cumulative length of stay methods, a single migration data asset, and the inclusion of people with Indefinite Leave in headline long-term international migration estimates.

The panel have a continued interest in the migration work programme, in particular the cumulative length of stay methods alongside the development of a migration data asset. They have also requested to see further validation of the methods developed for those with indefinite leave. Therefore, we will ensure the panel input is sought at key milestones rather than through a fixed meeting cycle.

Since the last report, two key publication updates supported the ongoing migration statistics work programme. In November 2025, the Office for National Statistics (ONS) published a suite of long-term international migration releases covering changes to methods and estimates, revised estimates using administrative data, and new methods for estimating EU+ and British national migration. In April 2026, ONS published an international migration research progress update, setting out further work to improve admin-based migration estimates and explore alternative definitions of migration, including research on migrant groups, British national migration, local authority estimates for children and students, and international temporary migration. These publications are available on the ONS website. 

Minutes for these meetings are available on the Authority website.