There are now 2,001 ISA millionaires in the UK with average pots of £1.4m.

There are 60 ISA-holders with pots of over £3m, with an average pot size of £6.2m.

An ISA holder with a £6m investment could expect to take home £434,000 tax free income annually.

Total ISA millionaire holdings in the UK now stand at £2.8bn, with annual tax-free returns to these investors exceeding £200m a year assuming 7% annualised growth, according to data from HMRC obtained by a Freedom of Information request by InvestingReviews.

While HMRC would not reveal the size of the country’s largest ISA pot, the data suggests it is likely there are several ISA investors sitting on pots in excess of £10m.

Among the largest ISA pot holders is Liberal Democrat peer Lord Lee of Trafford who became the UK’s first ISA millionaire in 2003, after maxing out his allowance from the time of their launch in 1987.

Currently there are approximately 2.7m Stocks & Shares ISA holders, of which 37% are maxing out their allowances.

Data from HMRC in June 2021 revealed 40% of high earners failed to take out an ISA in the 2018/19 tax year. 

In addition, only one in five of those earning over £100,000 per annum fully used their full ISA allowance in 2018/19.