The study of 2,000 British adults found that a lack of disposable income was the main reason people didn’t have either a cash or investment ISA.

The research highlighted a lack of understanding about ISA products in general.

Some 89% of people surveyed did not know the ISA allowance was increasing to £20,000 for the 2017/18 tax year.

When quizzed about cash ISAs, one in ten people said they didn’t have one because they incorrectly believed they wouldn’t be able to access their savings when they needed them.

Confusion was even greater when it came to investment ISAs, also known as stocks and shares ISAs. A third of people who didn’t have an investment ISA said they didn’t understand them, one in five felt they were too risky, and one in five said they wouldn’t know what to invest in.

With inflation on the rise, 65% of people polled claimed they were concerned about the impact inflation would have on their savings. However, only 17% felt they had a strategy in place to do something about it.

Clare Francis, Barclays’ savings and investment director, said: “With the Bank of England base rate at a record low, and inflation at its highest rate for more than three years, it’s more important than ever that people stay in control of their money and plan ahead.

“One strategy to combat inflation is to consider whether an investment ISA could be right for you, as stock market investments tend to outperform cash savings over the longer term. You’d be surprised how easy it is to open an investment ISA, and even if you can only invest a small amount each month, you can still build a sizeable, balanced portfolio over time, the returns on which are shielded from tax.

“However, there are no guarantees because stock market-linked investments can fall as well as rise, so it’s important to first make sure you’re comfortable with the risks.”