According to the Investment Management Association (IMA), net sales into fund-based ISAs reached £2.3bn up from £1.3bn in the 2012-13 tax year.

This is based on figures from fund groups and five fund platforms – Cofunds, Fidelity, Hargreaves Lansdown, Skandia and Transact.

The last five days of the tax year saw net retail sales of £358m, some £11m more than the same period last year.

Jason Hollands of Bestinvest said: “While a last minute stampede of net funds inflows might sound impressive, this will understate the true demand for Stocks & Shares ISAs as we find that many last-minute investors open their accounts with cash as they deliberate over where to invest it during the months ahead.”

Equities were the best-selling asset class in March, with net retail sales of £952m – ten times the levels of March 2013.

UK equity funds were the most popular, followed by Global, European and Japanese.

Both Asian and North American equity funds continued to see net outflows at £221m and £50m respectively.

Hollands said: “Interest in developed market equities is perhaps unsurprising after the strong returns during 2013, when shares re-rated dramatically with the support of quantitative easing in their sails.”

He continued: “While equities should still have the edge, shares in the developed markets are now firmly out of the bargain basement and – in our view – downright expensive in the US.”

Hollands believes the “easy money” phase is over for the asset class now that US growth is “floundering” and China’s growth is decelerating.

He said: “We are likely entering a period when picking the right stocks is going to be more important than it has been in recent years, when all ships were lifted by the rising tides of money printing.”