Thousands of Brits have foreign currency worth £1 billion lying about their homes, says M&S Money.
M&S Money says 80 per cent of Brits bring home £16 each every time they come back from their summer holidays - and never change it back into sterling.
Around a third of those hoarding foreign currency bring back over £50 in foreign notes and coins every time they go on holiday.
David Mackay, commercial director at M&S Money, said: "This year, 14 million travellers brought home at least £50 from their trip abroad."
"If they changed it back rather than forgetting about it, they could put the money towards a deposit on their next holiday or a short break," he added.
Over three-quarters of Brits said they "forget" to change back their leftover currency, while six in ten claim they will use their foreign notes and coins in future trips.
Changing money at an M&S bureau de change is free.To read more about Savings Accounts, click here.
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