A study released by The Pew Charitable Trusts showed that small banks in the U.S. have overdraft practices comparable to large institutions, which Pew says still fail to meet overdraft best practices.

In a Dec. 20 news release, Pew reported that two out of five banks structure transactions in a way that maximizes overdraft fees.

"The prevalence of fee-based overdraft programs at both large and small banks underscores the need for new policies to prevent 'courtesy' overdraft programs from being costly and unsustainable forms of short-term credit for many financially vulnerable consumers," Nick Bourke, Pew's consumer finance project director, said in the release.

After a review of disclosures from 50 of the largest banks, Pew reported that service charges on deposit accounts, which include overdraft and nonsufficient funds fees, have more than doubled while interest income has decreased during the past 30 years, and that most of the largest U.S. banks with consumer checking accounts continue to charge at least $35 each time an overdraft is incurred.

In addition, based on responses from 45 small banks across the U.S., Pew discovered that 42 of the 45 banks studied, rather than declining an ATM or debit card transaction that would overdraw a consumer's account, allow customers to opt in to overdraft service for ATM and debit card transactions, with a median fee per overdraft of $32. All the small banks studied allow customers to incur at least $90 in fees each day for any overdraft transactions.

The research firm recommended that regulators revise federal rules on overdrafts so that these programs are transparent and designed only for infrequent and accidental occurrences.