- The UK had an estimated 442,000 millionaires in 2025, down 7 per cent from a year earlier.
- The figure is the lowest since the 2008 financial crisis, according to the Adam Smith Institute.
- The think tank points to economic and tax changes, although official data does not support every claim.
The number of UK millionaires has fallen to its lowest level since the global financial crisis, according to fresh analysis by the Adam Smith Institute. The think tank estimates there were 442,000 adults with a net worth of at least £1 million in 2025, a 7 per cent drop from the previous year.
The institute's Millionaire Tracker, which uses data from the Office for National Statistics (ONS), counts adults whose total wealth—including property, pensions, savings and investments—is worth at least £1 million. While the report highlights several reasons behind the decline, not all of its conclusions are backed by official government data.
So, what is driving the fall?
1. Higher interest rates have reduced the value of assets
One of the biggest factors is the impact of higher interest rates since the pandemic.
When borrowing becomes more expensive, demand for assets such as property can weaken, while financial markets often become more volatile. At the same time, lower returns on savings have reduced the overall value of many households' financial assets.
Because millionaire status is based on net wealth rather than annual income, even relatively small falls in house prices or investment portfolios can push people below the £1 million threshold.
2. Tax changes have created uncertainty for wealthy individuals
The Adam Smith Institute argues that changes to the UK's tax system have made the country less attractive for high-net-worth individuals.
The report points to the abolition of the non-dom tax regime, which previously allowed some UK residents with permanent homes overseas to avoid paying British tax on their foreign income. The regime was replaced in April with a new system that exempts foreign earnings for up to four years for new residents and people returning to the UK after living abroad for at least a decade.
According to the think tank, such changes have contributed to uncertainty among wealthy individuals considering whether to live or invest in Britain.
3. More wealthy people are reportedly leaving the UK
The report also claims that Britain is seeing a growing number of wealthy residents leave the country or choose not to relocate there.
It argues that higher taxes and what it describes as a less welcoming environment for wealth creators have encouraged some high-net-worth individuals to move elsewhere.
However, official figures paint a more cautious picture. HM Revenue & Customs' latest data shows 60,700 non-doms were living in the UK in the tax year ending April 2024, and the tax authority has not found clear evidence of a large-scale exodus following the tax changes. That means the extent to which migration is affecting millionaire numbers remains open to debate.
4. Wealth has fallen in real terms, not just on paper
The Millionaire Tracker measures wealth using constant prices, meaning the figures are adjusted for inflation and changes in exchange rates.
This is important because it removes the effect of rising prices across the economy. In other words, the decline is not simply the result of inflation making money worth less. According to the think tank's methodology, it reflects a genuine reduction in the real value of assets held by many households.
5. The debate over taxes is far from over
The report has reignited a wider political debate about how Britain taxes wealth.
The Adam Smith Institute has called for the abolition of inheritance tax and lower capital gains tax, arguing these changes could encourage investment and help retain wealthy individuals in the UK.
Prime Minister Andy Burnham has previously said he would examine proposals to align capital gains tax more closely with income tax, although he has not committed to changing the rates. He has also suggested replacing inheritance tax with a care levy to help fund social care reforms.
Meanwhile, Andrew Griffith, the Shadow Business and Trade Secretary, reportedly said fewer millionaires could mean fewer investors, entrepreneurs and taxpayers contributing to the UK economy.
The latest estimates suggest Britain's millionaire population has been falling for four consecutive years after peaking at 1.07 million in 2021. However, the ONS does not publish annual millionaire figures, and its latest official data still shows 3.7 million households with net assets above £1 million, largely reflecting long-term growth in property values. That means while the Adam Smith Institute's analysis points to a clear downward trend, the broader picture of wealth in Britain continues to evolve.
