Net migration to the UK in recent years peaked at a higher level than initially estimated and has since fallen more sharply, driven by more British nationals leaving the country than previously thought, new figures show.
Improved methods by the Office for National Statistics (ONS) suggest net migration hit a higher and slightly earlier peak of 944,000 in the year ending March 2023, compared with the previous estimate of 906,000 for the year ending June 2023.
This was followed by a sharper fall than initially reported, with net migration in the year ending December 2024 now estimated to be 345,000, lower than the original estimate of 431,000 that was published by the ONS in May of this year.
Estimating our population in a changing world is complex, in a new article we look at what long-term international migration is, and how we produce estimates that are as timely and accurate as possible.
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The main factor behind the change in the figures is an improvement to the way the ONS calculates the immigration and emigration of British nationals, which is “consistently higher” than previously estimated – in particular the number who are leaving the country.
Some 257,000 Britons are now thought to have emigrated from the UK in the year ending December 2024, up from an initial estimate of 77,000.
At the same time, 143,000 Britons are estimated to have immigrated to the UK in this period, up from 60,000.
Net migration of British nationals has been running at a negative level for many years – in other words, more of this group leave than arrive – but the figure is now greater than initially estimated, standing at minus 114,000 in 2024, compared with an initial estimate of minus 17,000.
This larger negative figure has in turn helped bring down the overall estimate for net migration to the UK.
The previous estimates for the migration of British nationals were based on the International Passenger Survey (IPS), but this had become “stretched beyond its original purpose” of measuring travel and tourism and was based on a very small sample size, the ONS said.
Data collected as part of the 2021 census also suggested the survey was underestimating the level of migration of British nationals.
For its new figures, the ONS has for the first time used national insurance data from the Department for Work and Pensions to estimate whether UK individuals have recently immigrated or emigrated.
Improvements have also been made in the way the ONS estimates the movement of EU+ nationals, which covers the 27 countries of the European Union plus Iceland, Liechtenstein, Norway, and Switzerland.
These figures were previously estimated using DWP information but are now based on Home Office Borders and Immigration (HOBI) data, which are “a more direct measure of migration flows”, the ONS said.
This is because EU+ nationals require permission to migrate to the UK, typically in the form of a visa or by acquiring leave to remain, and this information is better captured by the Home Office.
This is the same dataset used for tracking non EU+ nationals since 2021.
Mary Gregory, director of population statistics at the ONS, said the independent statistics body has been exploring different data sources to overhaul its estimates, after the Census 2021 showed the International Passenger Survey was underestimating the number of British people abroad.
“Understanding the long-term international migration patterns of British nationals has been, and always will be, challenging due to the sheer number of British people crossing the border on a daily basis,” she said.
“Very few of these will be migrants and British people don’t need a visa to travel to the UK so we cannot use HOBI data to estimate migration of British nationals.
“Based on these new data and methods, it is clear the IPS continued to underestimate British emigration since 2021, and it also underestimated immigration.”
Research affiliate Georgina Sturge, of Oxford University’s Migration Observatory, said the new method “almost certainly” gives a more accurate picture of migration but “uncertainties remain”.
“The method for estimating migration of British citizens is very much experimental and future revisions are likely,” she said.
“But it is reassuring that the British emigration figure is now more plausible than previous estimates.
“Another uncertainty is that there is still no good method for taking into account EU and non-EU visa overstayers.”
The cumulative impact of these changes and revisions is that net migration to the UK across the four years from 2021 to 2024 inclusive is now estimated to be 2.55 million, down from a previous estimate for this period of 2.65 million.
The net migration estimate of 345,000 for the year to December 2024 is the lowest for any 12-month period since 251,000 in the year to June 2021.
The changes have been published ahead of the latest long-term international migration statistics in the year to June 2025, which will be released on November 27.
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