Why people immigrate to the UK: seizing the opportunities of administrative data

Image of departures and arrivals sign at Heathrow

The Office for National Statistics has launched a public consultation on the future of population and migration statistics. This includes seeking views from users about potential alternative definitions and breakdowns of population and migration that we don’t currently provide. One of those we’re already aware of is the need for more context on the drivers of international migration. Jay Lindop explains how we’re using administrative data to shed more light on the reasons people migrate to the UK.

Net migration in 2022 was at a record level, with around 606,000 more people coming to the UK than leaving. There are a variety of drivers behind this including people arriving for work and study, as well as for humanitarian purposes, including unique events such as those arriving from Ukraine and Hong Kong.

Up to this point we’ve been unable to produce robust estimates of net migration by reason. Historically, when producing estimates using the International Passenger Survey (IPS), this was not fit for purpose. While we had a good understanding of why people arrived to live in the UK, the IPS didn’t capture well those emigrating, why they were in the UK in the first place.

Thanks to our move to an administrative data-based system – including using visa and border data – we are able to address this for the first time. Our new methods reflect how individuals interact with official systems upon arrival and during their stay in the UK. For instance, we can look at the type of visas people travel on. This means we know why they are here right up to the point at which they leave. Having this information is of huge value to policy makers and service providers.

We’re aiming to harness the power of administrative data in this way for our next set of estimates in November, complementing our headline measure of net migration with net migration by reason. This will be particularly important for certain subgroups, including students and workers.

Reason for migration

We recognise that long-term student migrants in particular are more temporary than others, with about 60% on average leaving after their studies have completed. But we also know that some transfer onto other visas, such as work, adding a layer of complexity to this accounting exercise.

That’s why we presented options for measuring net migration of students in May.

It is possible to estimate a net flow that removes students using immigration by reason, and emigration by original reason for arrival, although it has some limitations. The advantage of this method is that it gives an idea of the role of student visas in the net migration to the UK and is consistent with our headline measure.

However, the disadvantage is that this method overlooks the movement between different visa types and the proportion of time a person might spend studying or working while in the UK and their contribution to that sector. For example, someone who arrived to study for a year, then worked for three years, would be counted as a student when they left. The contribution to the economy of the work element of their stay would be missed and therefore the driver of emigration could be misinterpreted.

Exploring different measures

Another option is for us to adjust the student inflow to account for transfers to other visas. This involves following the yearly intake of students (cohort) from their first visa at arrival through to their final visa before emigrating or naturalisation in the UK population. However, it may not be timely for our users to wait for the visa transfer or emigration of each student to understand this group.

To improve timeliness, we could explore another option estimating the proportion of students who transfer onto a secondary non-student visa, based on historical patterns. We could apply this to produce an alternative estimate of net student migration that excludes students who are likely to subsequently emigrate. However, historical patterns do not always reflect future ones, in particular, where new policies influence behaviours in migration such as the new graduate work visa.

In addition – and separate – to our usual net migration estimates, a fourth option, which relies less on assumptions, is producing a non-study immigration estimate which would include those students who have moved onto a non-study visa in the previous 12 months. These estimates wouldn’t align with headline migration estimates, as we would be counting some people who may have arrived (as a student) several years previously. This would provide a figure which completely excludes students who are still studying.

We’re currently analysing how each of these different measures, and others, play out in the data to give us the best additional insights on how the different reasons for immigration contribute to net migration.

We will continue to publish net migration statistics in our usual way. This is important as it shows how international migration, as defined by international standards, impacts on our society overall, including population change over time. As always, we’ll work with experts and partners across the Government Statistical Service to make sure we develop methods which best respond to user needs.

Further work

We’re also fully aware of the need to better understand migration journeys, namely, where people have migrated from. Our current estimates break it down by EU, non-EU and British citizens. Using the power of administrative data, especially visa data, we are confident we will, in time, be able to provide net migration estimates by nationality.


Providing users with additional measurements of the population and migration, based on alternative definitions to those we currently use, are part of the proposed approach we have set out in our Population and Migration Statistics Consultation.

The consultation runs until 26 October 2023 and asks users about a new approach to measuring the population.

Your input is essential. We are asking you to think beyond what is currently available, tell us where you see gaps in population and migration statistics and why having this information would be useful to you.


Jay Lindop is the Deputy Director of the Centre for International Migration

Jay Lindop is the Deputy Director of the Centre for International Migration