MARTIN Lewis has issued an urgent warning to holidaymakers over an ATM button you should never press when abroad.
The personal finance expert explained how using the seemingly harmless function on a cash machine could see you lose money.
Martin revealed that it is always best to take out cash or pay with a card in the local currency rather than letting an ATM or card machine convert the sum into sterling.
This is because a markup cost is added for doing the conversion, which could see Brits out of pocket on every transaction.
Martin said: "[The cash machine] says 'markup 4.5 percent', so they are adding a 4.5 percent load on top of the exchange rate.
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"You do not want this machine to do the conversion for you.
"You want your card company at home to do the conversion because, even if it's not a good card, it's a better rate.
"Continue with conversion? No way, it's going to cost me 20 quid more than it should."
He also advised using one of the specialist credit or debit cards that offer "near perfect" exchange rates and finding the cash machine with the lowest usage fee nearby.
It comes after he issued another warning to Brits travelling in Europe this summer, this time about the rules around two essential documents.
Meanwhile, on Martin's ITV show this evening, one man shared how one of Martin's tips helped him save £2,000 on his holiday, while one woman revealed how she saved £600 on airport parking using his advice.
Martin's show returned tonight for the second of a two-part special series, this time focussing on summer holiday tips.
As well as travel insurance, he advised viewers on the best debit and credit cards to use both in and outside of the EU and how to get the best exchange rates.
The show will return for a full series in October.
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