The claim that 16,500 millionaires fled Britain last year sounds alarming. But the number is nearly impossible to verify — and the real story behind Britain's wealthy is far more complicated than a simple headline suggests.
The Contested Numbers
Henley and Partners released their annual migration report with the UK ranking dead last for the first time: a net outflow of 16,500 millionaires. That figure has been quoted in Parliament, picked up by newspapers, and used to frame debates about Britain's global competitiveness. But verifying it is nearly impossible.
Tim Harford investigated this claim on his BBC podcast. He interviewed the head of research at New World Wealth, who explained that their estimates rely on social media profiles, press coverage, and company filings — not representative sampling. Harford argued that you couldn't draw conclusions from such a sample.
Dan Needle of Tax Policy Associates went further. In a forensic review published on his website, he pointed out that the report was riddled with statistical red flags. The firm had dropped all property wealth from its analysis between 2023 and 2025, yet its millionaire accounts barely moved — a result Needle described as impossible if the published methodology were real.
He found digit patterns in the data with a suspiciously high frequency of even numbers and numbers where trailing digits cluster on zeros and fives with almost no ones. Statistically, he points out, the chance of that occurring naturally is about one in 240,000. The numbers were likely manually created or adjusted rather than observed.
"The figures were likely engineered rather than observed."
This doesn't mean wealthy people aren't leaving Britain. It just means it's very difficult to know whether they are — because good data simply doesn't exist.
The Non-Dom Regime
The UK's non-dom tax regime was not a recent invention. It dates back to the very first income tax in 1799, introduced by William Pitt the Younger to fund the Napoleonic Wars. At the time, all residents were taxed only on UK income. In 1915, the rules changed: UK residents were taxed on worldwide income unless they could claim non-domicile status.
Non-dom describes a UK residence whose permanent home for tax purposes is outside the UK. Domicile under British tax law has always been a bit of a funny thing — it's the place someone considers to be their permanent home and where they have the closest ties, referring to their tax status rather than citizenship or resident status.
A non-dom only paid UK tax on money earned in the UK. They didn't have to pay tax to the UK government on money made elsewhere unless they transferred it back into the UK. For wealthy individuals, this presented an opportunity for significant and entirely legal tax savings — especially if they could claim a lower tax country as their domicile.
Attempts to reform the non-dom rules over the years were frequent. Labour nearly abolished it in 1974. Nigel Lawson tried again in 1988. During the financial crisis, the regime was tightened where annual charges were introduced for long-term non-doms. You had to pay £30,000 a year if you'd been resident in the UK for seven of the past nine years and £60,000 a year if you'd been resident for 12 of the past 14 years.
Each time adjustments were made, Treasury officials warned of tax flight, and ministers backed down. The fear was that driving the wealthy abroad would harm the economy more than it would benefit from taxing them on their foreign earned income.
In March 2024, then Chancellor Jeremy Hunt announced the abolition of the non-dom rule ahead of the general elections. In October, Labour Chancellor Rachel Reeves confirmed the policies end, extending it to offshore trusts to prevent inheritance tax avoidance. Now, foreign income and gains are taxed in the UK as they are earned once an individual has been resident in the UK for four years.
On top of that, inheritance tax will apply to worldwide assets after 10 years and continue for 10 years after departure. The excluded property trust loophole is closed and the concept of domicile for tax purposes has been retired.
The Office for Budget Responsibility says they expect up to 25% of non-doms to leave the UK. The Treasury forecasts £12.7 billion in revenue over five years.
What Actually Happened
Research from Warwick University suggests the fears of a mass departure may be overstated. When Osborne's 2017 change took effect, only 6% of affected non-doms left the UK. Those who stayed paid significantly more tax — on average an extra £100,000 per year — and the predicted mass exodus never came.
But there are other signals being reported too. Butler agencies report fewer placements. Wealth managers say some clients are leaving. And London's luxury property market has softened. None of this is conclusive, but it's not nothing either.
The Financial Times found a wave of company directors have left Britain since the government abolished its favorable tax treatment for non-domiciled residents and raised other duties on the wealthy. They analyzed Companies House filings looking for directors of UK firms who updated their addresses to overseas jurisdictions. In the most recent report, 3,790 directors reported leaving the UK — up from 2,710 the year before. The spike that occurred in April coincides with the new tax changes.
This is not a perfect methodology either, which the FT highlighted: plenty of wealthy people don't run companies and plenty of directors don't update their filings in a timely manner. But a trend is visible in the data.
A Global Competition for Wealth
Countries around the world are constantly adjusting their tax regimes to attract the wealthy.
Switzerland offers lump-sum taxation to high net-worth individuals where a flat tax rate can be negotiated with local government authorities. Italy introduced a €100,000 euro flat tax on foreign income in 2017, later raising it to €200,000. This has been popular with footballers, fashion executives, and hedge fund managers.
The UAE has no personal income tax and a 9% corporate tax above a million dollars. Golden visas are part of the strategy too — the UAE offers long-term residency to investors. Italy and Greece have property-linked visa schemes.
Last month, several senior bankers from Pictet, one of Switzerland's most prestigious private banks, relocated to Italy, where they could get lower taxes. The move triggered a tax debate in Geneva. A point of contention is that some foreigners in Switzerland pay less tax than citizens do. Critics argued that Switzerland's rigid enforcement was pushing talent away, while Italy's flat tax regime was pulling it in.
Wealth taxes are politically popular but economically fragile. According to Economics Observatory, the number of OECD countries with annual wealth taxes dropped from 12 in 1990 to just three today. The reasons for dropping them are consistent: low yield, high avoidance, and administrative complexity.
Mobility is no longer limited to billionaires. Increasingly, professionals in the upper middle class are making decisions about where to live based on tax, lifestyle, and legal stability. The barriers to relocation have dropped. Remote work, international schools, and digital infrastructure have made it easier to live abroad without severing ties to home.
In the United States, internal migration reflects similar patterns. States like Florida, Texas, and Tennessee, which have no state income tax, continue to attract high earners from California, New York, and Illinois. The shift isn't just about tax — it's also about housing costs, crime rates, and the quality of public services.
Digital nomad visas have added another layer. Estonia, Portugal, Barbados, and many other countries offer residency to remote workers earning above a certain threshold. These programs target professionals who aren't wealthy in the traditional sense, but have portable incomes and flexible careers.
Citizenship planning has become a cottage industry. Wealthy families now hold multiple passports, not for travel convenience, but for legal and financial flexibility. Some jurisdictions offer plan B citizenships — second passports designed to hedge against political or fiscal instability.
The wealthy have always been mobile. What's changed is the scale. Mobility now extends to a broader segment of the population, and governments are adjusting their policies accordingly.
Bottom Line
The claim that 16,500 millionaires fled Britain is nearly impossible to verify — but it's also not nothing. The real story isn't about mass exodus; it's about how Britain's tax competitiveness has fundamentally changed in ways that make it harder to attract global wealth. The abolition of the non-dom regime marks a decisive shift: the UK is no longer a tax haven for the globally mobile. What remains unclear is whether the revenue projections hold, and whether the wealthy will actually leave — or simply adjust their tax strategies while staying.