An option for when they leave the plastic card at home.
Two UK banks, Royal Bank of Scotland and NatWest, have introduced the option in which customers use their banking app to request up to £100. They are then given a six-digit code to type into the ATM keypad to withdraw the money.
Clearly, the process is more fiddly than using a card, so is really designed for emergencies.
"It is a really simple and secure way to help our customers get cash whenever and wherever they need it," said Ben Green, head of mobile at RBS and NatWest.
The app is currenly installed in around 2.6 million handsets.