The Association of Investment Companies (AIC) says many investment companies and their managers will have systems in place to accommodate the ‘cooling off’ period, meaning they will not all accept ISA applications up to 5 April.

Annabel Brodie-Smith, communications director at the AIC, says that despite volatile equity markets, over the long-term they normally outperform the returns on ISAs offered by banks and building society.

She added: “The countdown to 5 April has begun and investors still to use this year’s ISA allowance may need to get their skates on. Whilst there is three weeks to go, it’s important not to get caught out as a number of investment company ISA deadlines fall before this date.”

The AIC recommends cautious investors consider phasing their ISA investment. For example, some groups allow you to drip-feed your money into the stockmarket over the next tax year so long as they receive your application before their deadline.

Brodie-Smith said: “Regular saving is well suited to choppy markets, smoothing out the peaks and troughs of the market and this is an option that might be worth exploring.