The High Court has given ANZ/ National Bank customers until December 13 to sign up to a lawsuit against the bank over fees, according to a group taking the case.
Fair Play on Fees lawyer Andrew Hooker lodged documents against the ANZ - New Zealand's largest bank - in June.
At the time, about 13,500 ANZ/National Bank customers had registered to take part and there was no guarantee that others would be able to join it.
Hooker said the court ruling would give thousands more people the opportunity to sign up.
"We are very happy for those ANZ/National Bank customers who came to us wanting to join the campaign after the court documents were lodged. We have over 1000 clients in this situation."