A widely cited report on millionaires leaving Britain has been criticised for making unsubstantiated claims, as its author admitted the study for years wrongly claimed to record property wealth.
New World Wealth (NWW) produces an annual estimate of the global number of rich individuals, along with figures for millionaires who have migrated to other countries.
This year’s report estimated 16,500 millionaires would leave the UK, on top of an outflow of 9,500 in 2024 — departures that critics have blamed on chancellor Rachel Reeves’ first Budget, which abolished the non-dom regime and imposed inheritance tax on more estates.
But the lack of official, credible data relating to the effects of the 2024 Budget on the UK’s wealthy population has fuelled political and economic arguments.
Andrew Amoils, the founder and sole employee of South Africa-based NWW, told the Financial Times there was “just a lack of information around and we’ve tried to fill the gap as best we could” on the migration of rich individuals.
“The fact that it’s been so heavily linked to non-doms is a little unfortunate because, to be honest, we don’t know whether someone is a non-dom or not,” he added.
Amoils’ Wealth Migration Reports are published in association with Henley & Partners, a London-based consultancy that markets schemes selling passports and residency permits in more than 40 countries.
The report has come under fire from Dan Neidle, founder of the Tax Policy Associates think-tank, who said that “until an independent audit is carried out, the Wealth Migration Report should be treated as marketing material, not evidence.”
Neidle noted that the report relied heavily on LinkedIn data, which was “not reliable” for finding someone’s tax residence, as opposed to the location where they were working.
He also pointed out that a 2025 NWW report’s definition of “private wealth” included bonds, gold and crypto holdings but not property, unlike previous editions.
This change should have led to a sharp drop in the number of dollar millionaires reported if their property was now excluded, Neidle said. Instead the 2025 report showed an increase.
His analysis also found that the patterns of digits in the data, such as the numbers of millionaires, centimillionaires and billionaires in each country, deviated from what would be expected in real-world numbers, suggesting that they had been inputted or adjusted manually.
This is because they exhibited more odd numbers, zeroes and fives than would be expected in a random sample of data.
Amoils told the FT he tracked 150,000 individuals’ changes of location using LinkedIn and other sources including international schemes selling residency or citizenship, such as Henley & Partners, corporate registers and data from “high-end international removal firms”.
“We track city location, company details and sector details for all 150,000,” he said, declining to give further details on how he keeps the information updated. “We also have hobby and university details for over 40,000 of them.”
Amoils admitted that the definition of “private wealth” had changed in the recent report, adding: “As far as I know we’ve never really included property in the numbers themselves. The benchmark numbers when we estimate somebody’s wealth, we try and strip out property.”
Amoils said the wording of the methodology was changed because there had been “a lot of question marks about why our numbers were so much lower than Credit Suisse’s numbers [in the bank’s own wealth reports] . . . We probably had to refine the methodology to explain that.”
He declined to comment on the digit patterns. Amoils said liquid wealth, including bond and crypto holdings, was assessed by looking at the wider market and then distributing those figures at a population level, rather than tracking individual holdings.
“We’re not checking every one on our database. We’re doing it on an aggregate basis for each country. And then we’re modelling each country against one another in terms of various metrics.”
Amoils, who has a master’s degree in economics from the University of Johannesburg, worked as an equity analyst before turning to wealth analysis in 2011 and founding NWW in 2013.
The company has had three employees at most, Amoils said, and its recent reports include The Rise of Florida, Tech Hubs of the Future and Australia’s Great Advantage.
According to NWW’s figures, there were 10.5mn dollar millionaires in the 10 richest countries at the end of 2023, rising to 10.9mn in 2024.
Madeleine Sumption, director of the Migration Observatory at Oxford university, also said the figures were “not reliable” because they were extrapolated from a sample of rich workers on LinkedIn and “assum[ed] all the UK’s millionaires behave in the same way . . . This is unlikely to be true.”
Alan Manning, a professor of economics at the London School of Economics, said it wasn’t “totally crazy” to use LinkedIn data for migration, but that millionaires presented particular difficulties and NWW should be “more transparent” about its model.
The dispute around NWW’s method highlights the wider gap in information on the number of millionaires in the UK — and the extent to which they are moving overseas as a result of the government’s tax policies.
Anecdotal evidence of an exodus of rich people has sparked concerns that Labour’s changes to the non-dom tax policy will lead to so many departures that it fails to raise money for the Treasury.
Official HMRC figures for those non-doms who have left will not be available until 2027. The FT has in the past cited NWW’s statistics.
Henley & Partners did not respond to a request for comment.