Three in five millionaire investors have considered leaving the UK because of rising taxation and the threat of higher taxes, according to new research.
The research also found that more than one in 10 (16%) of the 341 millionaires surveyed by HNW investment service Wealth Club for the research said they were actively considering becoming a non-UK tax resident.
Based on recent estimates of 442,000 UK millionaires (Adam Smith Institute figures), about 44,000 millionaires are believed to be currently contemplating ditching UK resident tax status.
An additional 45% said they had considered doing so but were unlikely to move.
Just a third (36%) said they had never considered leaving the UK because of tax.
Taxes were a major concern for almost all of the investors surveyed, with a general expectation that the tax burden on them will increase further.
Nine in ten (97%) believed taxes will definitely or probably increase in the UK over the next 12 months, with more than half (53%) convinced tax rises were inevitable.
Inheritance tax was the tax rise that concerned respondents most (22%), followed by wealth taxes (21%) and capital gains tax (18%).
Almost half (47%) identified higher taxes as the single biggest threat to their wealth, while a further 26% cited government policy. Together, these ranked well ahead of inflation, market volatility and geopolitical events.
Chancellor John Healey faces pressure to raise billions of pounds in his first Budget this autumn on 28 October to offset higher borrowing costs and plans for expanded social care.
Prime Minister Andy Burnham has previously said that Britain under-taxes workers and under-taxes wealth, leading to speculation about potential additional wealth taxes being on the table for the Budget.
However, the number of millionaires in the country has already fallen and is continuing to fall. The number of UK millionaires fell to 442,000 to its lowest level since the Global Financial Crisis in 2025, the lowest level since 2007 and around 7% lower than a year earlier.
There has been a considerable drop in the number of adults in the UK with more than £1m in net worth since peaks seen in 2020/21, according to think tank The Adam Smith Institute.
According to data from the free market think tank, the top 1% of earners pay 29.1% of UK income tax. It added that France, Austria and the Netherlands all abandoned plans for wealth taxes after seeing outflows of millionaires or other avoidance behaviour.
Alex Davies, founder and CEO of Wealth Club, said: “What is often overlooked is where this wealth came from. Almost all the investors we surveyed built it themselves through work, starting businesses or investing over many years. The overwhelming majority earned it.
“This matters. These are the people who work hard, create businesses and jobs, invest in growing companies and generate significant tax revenues. Governments inevitably face difficult choices and must balance the public finances. However, every tax rise and every policy change that makes Britain a less attractive place to save, invest and build businesses risks encouraging more wealth creators to look elsewhere. That would ultimately leave the UK poorer, not richer."
Of those surveyed, most had built their own wealth. Around 12% had accumulated most of their wealth by starting a business, 11% through self-employment, 40% through employment earnings and a further 33% through investing. Just 2% said inheritance or family wealth was the main source of their wealth.
• Wealth Club surveyed 341 clients with an average wealth of around £4.5m during July. The Adam Smith Institute's Millionaire Tracker estimates the number of UK millionaires each year from 1998 to the present.