The National Consumer Agency has advised shoppers buying vouchers or gift cards to use them quickly.
The group says that around 50% of Irish shoppers intend buying vouchers or gift cards this Christmas.
However, research shows that almost half of people who have received vouchers in the past have let them expire without using them.
Fergal O'Leary, director of research and policy with the NCA, said that anyone who receives a card or voucher should use them quickly.
"99% of people, if they use the vouchers quickly, then there wouldn't be any problem with them," he said.
"The problem that we have is, as our research has shown, about half of people who have got a gift voucher and haven't used it within the allowed time, and that is just money wasted."
"So the advice is simple - use it as quickly as you get it, and don't just forget about it."