Nationwide Building Society is trialling a "smart window poster" that people can tap with their contactless cards to make donations to a homeless charity.
When a person taps their card against the poster, which is next to a Nationwide cash machine in Bath, £3 is donated to local homeless charity Julian House. People can tap multiple times.
Nationwide says the plan is to make it easier for people to donate money and to instil confidence in people who feel uncomfortable giving cash directly to the homeless.
The trial raised about £100 a day, with all funds going to the Julian House Good Start fund, which helps to improve homelessness in the area.
As cash becomes less common, other groups are increasingly turning to contactless technology to help the homeless.
Sellers of the Big Issue, a magazine sold by the homeless on high streets across the UK, are now able to accept contactless payments cards following successful trials with Swedish mPOS vendor iZettle.
A year ago, London began installing donation points around the city where people can give £3 a tap to a pool of 22 charities comprising the London Homeless Charities Group.
In December Nationwide invested in app-based charity donation startup Percent.