Investors pumped £745m of new capital into venture capital trusts (VCTs) in the last tax year, the second highest sum on record.
The amount placed into the investment vehicle was more than the £570m raised during the previous tax year.
Jason Hollands, managing director of business development and communications at Tilney, said: "The growth has largely been the result of investors being concerned that the VCT rules were going to be changed, because there was a Treasury review last year, which left every option on the table.
"I think fundraising for the tax year we are currently in is likely to be about a third lower, as there is greater clarity over the rules."
The data revealed that 15,120 individuals claimed VCT tax relief in the 2016 to 2017 tax year.
Mr Hollands said: "This shows the relatively narrow investor base for these products."
Alex Davies, chief executive of Wealth Club, said: "HMRC's annual report into VCT funding reaffirms their popularity amongst wealthier and more sophisticated investors.
"It is hardly surprising they are becoming an increasingly mainstream investment choice – the restrictions on pensions mean they are one of the last relatively simple and tax efficient investments left for wealthier investors.
"Performance over the last 10 years has also been good."
The data showed that 41 per cent of investors claimed tax relief of £10,000 or less on their VCT investment.