The number of individuals with more than £1m in their ISA accounts climbed more than 50% in the 2023/24 tax year, an FOI request shows.
There were more than 7,730 ISA millionaires at the end of 2023/24, up from 5,070 in the previous tax year.
There was an even larger rise in the number of people with more than £2m stashed in their ISAs, which climbed 59% to 430.
The figures obtained by wealth manager and Glasgow-based Financial Planner Murphy Wealth also revealed that 40 people managed to build up pots of more than £5m.
It said HMRC would not disclose the number of individuals with more than £10m in their ISA accounts, which suggests that the figure could be between one and five.
Lord John Lee of Trafford is widely recognised as the UK’s first ISA millionaire, having reached seven figures in 2003. The former Conservative MP and peer has said that he achieved the milestone by investing in UK equities, focusing on small-cap companies, high dividends and patient, long-term investing.
Adrian Murphy, CEO of Murphy Wealth, said: “The rapidly rising number of ISA millionaires shows what can be achieved through patience, time in the market, consistent use of ISA allowances, and the effects of compounding.
“A previous FoI request we made showed that almost all ISA millionaires built their wealth by holding stocks and shares, while none achieved that status through cash alone. This underlines why more people in the UK need to consider investing their savings.”
He said attitudes towards investing were changing and that trend is only likely to accelerate with the changes to the ISA allowance that come into effect in April. People under the age of 65 will then be able to subscribe only £12,000 to cash ISAs (cut from £20,000), with the remaining £8,000 available for investment in stocks and shares.
Building a £1 million ISA pot would take around 20 years if a saver used the full £20,000 annual allowance and achieved an average annual return of 8%. The MSCI World Index – a basket of more than 1,000 of the world’s largest stocks – has delivered an average annual return of 9.3% over the past two decades.