Large banks could tap into a $500 million source of revenue annually if they charged customers for using mobile banking apps $1 to $3 a month. As per an S&P Global Market Intelligence survey, which states that 40% of its 4,000 respondents would pay a fee for such a service, although some users did say they would switch banks if charged. More than 90% of mobile banking users check their balances on mobile devices, while 48% deposit checks and 47% pay their bills.