Mobile card readers have increasingly been used by homeless citizens as the number of people carrying cash in Britain has sunk over the past few years.
William's office declined to comment on the report.
Prince William, his wife Kate and the rest of Britain's royal family recently celebrated the Platinum Jubilee, marking Queen Elizabeth's 70-year reign, with four days of festivities.
As children, William and his brother Harry were taken on visits to homeless shelters by their mother, the late Princess Diana, as part of her charity work.
