The number of ISA millionaires has now shot up to more than 4,000, according to freedom of information (FOI) request by The Openwork Partnership.
The latest figures come 20 years after Liberal Democrat peer Lord Lee of Trafford became the first publicly declared ISA millionaire in 2003.
Many of the early ISA millionaires would have made their fortunes in the Bolton and Invesco Equity Income accounts.
There are now almost ten times more millionaires, who have benefitted from maxing out their allowance, since 2016.
The findings showed the 50 top investors are sitting on average pots of more than £8.5mn, while the average ISA millionaire pot stands at almost £1.4mn.
Nearly all the millionaires are believed to be stocks and shares investors.
ISAs were launched, as PEPS, in 1987 with an annual allowance of £2,400.
Today, investors can pay in up to £20,000 each year with contributions not subject to income and capital gains tax.
The figures are correct as of April 2021 and nearly double the high of £2,000 millionaires recorded in 2019.
Setul Metha, head of partnership services at The Openwork Partnership said: “The ISA has not only created thousands of millionaires, but it has also empowered millions of ordinary investors to build a nest-egg alongside their pension. It is perhaps the best tax-free investment wrapper in the Western world.
“Of course, becoming an ISA millionaire takes time, money and a little bit of knowledge. But the rise in personal finance content online means the roadmap to millionaires’ row has never been more clearly signposted.”
