The banking ombudsman will begin publishing customer complaints as part of a scheme to improve consumer experience across the sector.
The complaints will be published on an online dashboard, giving an overview of the types of issues customers are reporting and how banks respond.
Banking ombudsman Nicola Sladden said the initiative had been in the works for about 18 months and was partly prompted by the joint regulators review into banks conduct in 2018.
"One of the recommendations from coming out of [that review] was for the banks to strengthen their conduct and risk management systems and I think capturing complaints and reporting on them was one of key outcomes."
Sladden said the new dashboard, which goes live today, would promote transparency in the sector and would encourage banks to learn from customer's complaints and improve their services accordingly.
The dashboard breaks down complaints by product and service type (such as credit cards, investments, insurance and processing methods) and the underlying problem (such as transaction error, faulty advice or information and unwarranted or excessive fees).
It also shows how long each type of complaint took to resolve and what the outcome was.
Complainants are also profiled by age, gender, location and whether an individual, business or trust.
Sladden said while it was important to understand what people were complaining about in the banking sector, it was also imperative to get a gauge on who was and who was not complaining.
"I think it's well understood that the most vulnerable consumers that often do not have the confidence or courage to make a complaint and it's incumbent on all agencies to look at what more they can do to make their service more accessible.
"Whether it's a bank to try and understand and encourage those voices to be heard or whether it's an agency like ours, in terms of how we make our services more accessible for all New Zealanders."
The country's retail banks have collectively agreed to provide their customer data to the banking ombudsman each quarter so it can published on the dashboard.
Sladden said she expected the banks to comply, but if they did not there were options available.
The banking ombudsman could seek a response from the bank, put a notice on the dashboard saying that certain information is missing and if necessary seek support from the regulators to encourage and require compliance.