Banks increasingly rely on customer-unfriendly overdraft fees to make up revenue they aren’t getting from loans, according to a new report that will provide another problem for an industry already in trouble over customer service scandals.

Most big banks charge at least $35 each time an overdraft is incurred on a checking account, the Pew Charitable Trusts reported in a study Tuesday. More than 40 percent of banks structure transactions in such a way as to maximize overdraft fees, and 80 percent allow overdrafts on ATM and debit transactions.