According to comparison site uSwitch.com, the 12 million holidaymakers planning to use a debit card abroad not only face an average exchange rate fee of 2.75%, but they will also be charged a ‘purchase’ fee of around £1.25 per transaction.

This means a customer paying a £100 restaurant bill on their debit card abroad could typically end up being charged £104 for the meal – whereas if they paid on their credit card they would be charged £102.75 in total.

Michael Ossei, personal finance expert at uSwitch.com, said: “Travelling abroad is expensive enough without the extra penalties for using the wrong card while you’re there. Financial awareness may go into holiday mode, but a high credit card bill is one holiday hangover you can do without.

“Too often we rely on the convenience of plastic without thinking about the extra fees that may apply, but with some planning ahead it’s possible to escape the hefty charges. The simple rule is, if you want to use a card on holiday, use a credit card for spending and a debit card for withdrawing cash. There are credit cards on the market that charge no transaction fees when you use them abroad – these are the ones to go for.

“Alternatively get a pre-paid currency card which offers the convenience of a credit card without the borrowing and allows you to top up foreign currency, some with no commission charges. The best thing about currency cards is that you can only spend what you load on them so you are guaranteed not to overspend.”

Holidaymakers who prefer to pay in cash are being advised to take both exchange rates and commission rates into account to get the best deal on their holiday money.

This will normally involve pre-ordering the currency and collecting it before traveling. Consumers are reminded that they should avoid changing currency at the airport or straight from their debit card, as commission fees usually eats into a holiday budget.