In its report, the commission said that competition was stifled at the expense of customers, with unclear charges and restrictions, adding to the likelihood of consumers getting into debt.
“A lack of clarity on charges and unduly complex charging structures and their application, combined with a reluctance among customers to switch providers, are restricting competition in the market for personal current accounts in Northern Ireland,” the commission said.
“These features make it likely that customers incur higher charges and receive lower levels of credit interest than they might expect in a more competitive market.”
Investigations have been taking place for nearly 18 months following a “super-complaint” about banks in Ulster and the debt this could be causing customers.
Chairman of the Competition Commission, Christopher Clarke, said that such practices could set a precedent for other UK banks and result in less choice for consumers.
“Without this competitive pressure from customers, banks are likely to levy higher charges and pay lower rates of interest than might be expected in a more competitive market,” he stated.