What is international migration and how do we estimate it

How a person travels to the UK, where they travel from and their purpose for staying in the country all affect how they might be counted in our statistics.

We used to estimate migration using a survey that questioned a sample of people at UK airports, seaports and the Channel Tunnel about their intentions, called the International Passenger Survey.

However, this had limitations, as we could only base our estimates on what people told us about their plans. We have been working to reduce our reliance on this source, and utilise newly available administrative data from the Home Office and Department for Work and Pensions to create more accurate estimates, based on people's actual behaviour.

Bringing these different sources together is complicated, and these methods are still in development. We have been using Home Office data on visa and asylum applications to count migrants from outside EU+ countries in recent years.

More recently, we have published new research explaining our new approach to capturing migration of EU+ citizens and British nationals.

You can find out more in Understanding international migration statistics.

Throughout this article, we have included examples of possible migrant journeys to demonstrate how different people are counted in our data, and to show the complex real-life situations that our methods need to account for. All names and scenarios used are fictional.

Migration to and from non-EU+ countries

The Home Office routinely collects data on visa applications, asylum claims and other humanitarian migration routes. We use these as a starting point to estimate the migration patterns of people from countries outside the EU+ area.

While these are important information sources, they do not show us the whole picture regarding migration on their own. The record of how many long-term visa applications are made and granted does not directly reflect the number of individuals coming to live in the UK long-term. For example, not everyone issued a visa travels on it. We also cannot tell from this information alone when a person leaves the country.

Example: Migration for study

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Others might apply for a long-term visa after arriving in the country, or enter as a short-term traveller, or without documentation at all.

As a result, it takes time, both to identify as many migrants in our statistics as we can, and to confirm whether they will stay long-term.

Example: Seeking asylum

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In certain cases, the UK offers humanitarian protection via specific visas, such as those issued through the Ukraine scheme or Afghan resettlement scheme.

We group people who move to the UK on humanitarian visas separately to those seeking asylum, as the terms of their stay are slightly different, but all those in the UK for at least 12 months still contribute to our long-term international migration estimates.

Migration to and from EU+ countries

Since 1 January 2021 (when the Brexit transition period ended), citizens of EU+ countries no longer automatically have freedom of movement to live and work in the UK long-term. Now, they can either qualify for EU settled status (EUSS), which is open to EU+ citizens who were already resident in the UK, or they must apply for an existing visa route.

For those who travel via a visa route, we are beginning to use the same Home Office Borders and Immigration (HOBI) data and methods that we do for non-EU+ nationals.

By comparing the start and end dates of an individual's visa with their first arrival to and last departure from the UK, we can estimate the number of people granted long-term visas who end up travelling on them and remaining in the country for a year or more.

Example: Migrating for work

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However, people with EU settled status, or Irish nationals, do not need a visa to move to the UK. Therefore, to estimate migration of these groups, we need more information.

For those with EU settled status, we use the same travel data from the Home Office to identify those who are newly emigrating out or migrating into the UK.

Without information from visa applications, we only have information on people's travel into and out of the country. This is not enough information, as most entrances to or exits from the UK are not a person making a long-term move. Many people with settled status may have been resident in the UK for a long time, and they are appearing in Home Office figures due to short-term travel.

Because of this, we use extra assumptions to identify the cases where a person with settled status is moving into or out of the country long-term. This involves a range of steps, including looking at the cumulative amount of time they spend in and out of the country in a given year. We also need to make assumptions about behaviour where data on a person's travel into and out of the country is incomplete.

You can find our more in Implementing new methods for estimating the international migration of EU+ nationals, progress update: November 2025.

Example: Migrating with EU settled status

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Estimating migration of Irish nationals adds further complication, as not only do they not require a visa to live and work in the UK, they are also often not recorded in Home Office travel data, as there is an open border between Northern Ireland and the Republic of Ireland.

In this case, we use additional data from the Department for Work and Pensions known as the Registration and Population Interaction Database (RAPID).

This allows us to identify Irish nationals who pay taxes or claim benefits in the UK using their Irish documentation. This helps us to produce better estimates of Irish nationals moving into and out of the UK long-term in a given period.

Migration of British nationals

When British nationals migrate in and out of the country, they still contribute to population change, but they do not require a visa or other permissions to do so.

This makes identifying long-term migration of British nationals a particular challenge. Millions of British citizens enter and leave the country on a regular basis, and most of these journeys are short-term holidays or business trips.

Similarly to our approach in estimating long-term migration among Irish nationals, to produce the best estimates we can of British nationals moving into or out of the country long-term, we utilise the Department for Work and Pensions (DWP)'s RAPID dataset, which captures interactions with the UK taxes and benefits system.

This dataset is not designed to count migration. But, using information on when people start or stop paying UK taxes, claiming benefits or interacting with the education system, we can estimate arrivals to and exits from the UK.

Example: Retiring abroad

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As with estimates based on Home Office data, we need to carry out extra analysis to make our figures as accurate as possible. There are many reasons that a person may not appear in the taxes and benefits system in a given year, without them necessarily being out of the country.

This might include someone transitioning from a job where they are on a payroll to more casual, cash-in-hand labour, meaning they are no longer active in the tax system. Some residents may neither work nor claim any benefits, again leading to them being missing from DWP's data.

We have found that older adults in particular, (aged 45 to 65 years) may interact with these systems less than other age groups. This is because they are more likely than other age groups to have the means to live without working or claiming benefits.

Children, too, can be harder to estimate, as if a parent is not claiming child benefit on their behalf, they will not appear in the data.

We therefore have to make further adjustments to our estimates to account for these differences in coverage for certain groups.

While this method is generally reliable for creating migration figures for some British nationals, the data we use are not updated when a person naturalises to become a British national.

To estimate migration journeys among these British nationals, we need to use extra data sources to estimate the number of people who may have naturalised to become British nationals, and then subsequently migrated after naturalising. You can learn more in our Implementing new methods for estimating the international migration of British nationals, progress update: November 2025.

Emigrating as a naturalised British national

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