There's money to be made for banks that offer low-cost deposit accounts to previously unbanked or underbanked households. That's one of the key takeaways from a recent Federal Reserve Bank of St. Louis report that looks at new account openings, debit transactions and online banking activity, associated with Bank On checking accounts. Bank On accounts, offered by dozens of banks, must charge no overdraft fees and no-fee debit cards, among other things, as designated by the nonprofit Cities for Financial Empowerment Fund. Last year, customers at 17 financial institutions opened 2.2 million new Bank On checking accounts. Among those, 82% were new customers and 79% regularly used online banking options, the St. Louis Fed said in a report based on information submitted to its Bank On National Data Hub.