Britain’s millionaire population falls to lowest level since the financial crisis

Britain’s millionaire population has fallen to its lowest level since the aftermath of the global financial crisis, highlighting the impact of higher interest rates, weaker asset values and growing concerns over the country’s competitiveness for wealthy investors.

Research by the Adam Smith Institute estimates that just 442,000 UK adults held net assets worth at least £1 million in 2025, a 7 per cent decline from the previous year and less than half the peak of 1.07 million recorded in 2021.

The think tank’s analysis, based on Office for National Statistics wealth data adjusted for inflation and currency movements, suggests Britain’s millionaire population has contracted for four consecutive years as rising borrowing costs have weighed on property prices, investment portfolios and savings returns.

The report also argues that the UK’s tax environment has become a growing factor in wealth migration. It points to the abolition of the non-dom tax regime, relatively high tax rates and what it describes as an increasingly less attractive environment for entrepreneurs and investors.

Andrew Griffith, the Shadow Business Secretary, said a shrinking millionaire population should concern policymakers because wealthier individuals contribute disproportionately through taxation, investment and job creation.

The findings add to a broader debate over Britain’s fiscal strategy as Prime Minister Andy Burnham considers changes to capital gains tax and inheritance tax ahead of his first Budget.

The Adam Smith Institute has urged ministers to abolish inheritance tax and reduce capital gains tax rates, warning that higher taxes could accelerate the loss of high-net-worth individuals.

However, the picture remains contested. While wealth migration reports have highlighted a growing outflow of affluent residents, HMRC data has not indicated a large-scale exodus of former non-doms, and recent studies suggest departures among high earners have been more limited than initially feared.

The debate leaves ministers balancing the need to raise revenue against maintaining Britain’s appeal as a destination for investment, entrepreneurship and wealth creation.