- The number of ISA millionaires rose from 5,070 in April 2023 to 7,730 a year later.
- The average ISA millionaire held investments worth £1.348 million, while the top 25 averaged nearly £12 million each.
- The cash ISA allowance for under-65s is due to fall to £12,000 from April 2027, although the overall annual ISA limit will remain £20,000.
The number of ISA millionaires in the UK has jumped by 52 per cent in a year, with 7,730 people holding tax-free investment pots worth at least £1 million, according to figures from HM Revenue and Customs (HMRC).
The data, obtained through a freedom of information request by financial app Plum, showed an increase of 2,660 people from the 5,070 recorded in April 2023. The figures relate to holdings as of April 5, 2024, and were rounded to the nearest 10.
The figures highlight how long-term investing and compound growth can help build substantial wealth within Individual Savings Accounts (ISAs), which allow eligible savings and investment returns to grow free from UK income tax and capital gains tax.
Will Bryant, director of wealth strategy at Plum, reportedly said: “A jump of more than 50% in a single year is really telling.”
He said ISA millionaires were not people who had “suddenly saved” their way to £1 million.
“It’s the result of years of patient investing, where the growth on your growth starts doing the heavy lifting. That’s the bit people underestimate,” he said, according to reports.
How much do ISA millionaires have invested?
HMRC’s figures showed that the average ISA millionaire held a portfolio worth around £1.348 million in April 2024.
Most of the investors, approximately 7,300 people, had ISA holdings between £1 million and £1.999 million. Around 60 people held pots worth £4 million or more, with the average value in this group reaching £7.708 million.
The mean market value among the 25 largest ISA holdings was £11.928 million.
HMRC cautioned that the figures should be treated as a guide. ISA managers submit information about individual accounts annually, but some records may contain errors or fail to arrive, meaning the data may not capture every holding accurately.
Bryant said the figures underlined the importance of taking a long-term approach to investing, despite geopolitical uncertainty and market volatility. He also pointed to the performance of global markets, particularly US equities, as a factor supporting portfolio growth.
However, there is no guaranteed route to becoming an ISA millionaire. Returns depend on investment choices, market performance, fees, the amount invested and the time money remains invested. Shares and funds can fall in value, and past performance does not guarantee future returns.
What is changing for ISA savers in 2027?
The figures come as the Government prepares to reduce the annual cash ISA allowance for people under 65 from £20,000 to £12,000 from April 6, 2027. The overall annual ISA allowance will remain at £20,000, while people aged 65 and over will retain a £20,000 cash ISA limit.
The change means eligible savers under 65 will still be able to contribute up to £20,000 across their ISAs, but no more than £12,000 of that annual allowance can go into a cash ISA. The remaining £8,000 can be allocated to other eligible ISA types, subject to the applicable rules.
Bryant said the changes could encourage some savers to put more money into stocks and shares ISAs to use their full tax-free allowance, but warned that many people might not yet understand what was changing.
HMRC figures released in September showed that £135.7 billion was subscribed to adult ISAs in the 2024-25 tax year, an annual increase of £32.7 billion. Cash ISA subscriptions rose by £26.1 billion, or 37.5 per cent, while stocks and shares ISA subscriptions increased by £6.1 billion, or 19.7 per cent. Lifetime ISA subscriptions rose by £472 million, or 20.1 per cent.
Financial experts have stressed that ISAs can help people at different stages of life, whether they are building an emergency fund, saving for a home or investing for the longer term.
Charlene Young, head of technical at AJ Bell, said investors aspiring to build a seven-figure ISA should start as early as possible and adopt a “get rich slow” mindset.
“There isn’t a single, sure-fire route to becoming an ISA millionaire,” she said, adding that a diversified portfolio held over the long term was generally more suitable for ordinary investors than trying to chase unusually high returns.
The rise in ISA millionaires demonstrates the potential of tax-efficient investing over time, but it also reflects the resources available to people who can invest substantial sums and leave them untouched for years. For most savers, the priority is to build a sustainable habit, understand the risks and choose investments suited to their financial circumstances.
