Kiwibank reported to the commission in August last year that it had failed to have in place robust home loan variation disclosure policies, procedures and systems for certain types of home loan variations in the period before April 2019.
Customers eligible for the remediation will be contacted by Kiwibank and any enquiries should be directed to the bank.
Under the CCCF Act lenders entering into or varying consumer credit contracts after June 6, 2015 were required to meet lender responsibility principles as set out in the Act.
The lender responsibility principles require lenders to exercise the care, diligence, and skill of a responsible lender always, including during all subsequent dealings with borrowers and guarantors.
They must also treat borrowers reasonably and with respect.
Kiwibank chief executive Steve Jurkovich said it had proactively identified the issue and reported it to the Commerce Commission, and had worked constructively since then to resolve it.
"We apologise to customers and would like to reassure them that our systems and processes have been improved to ensure we deliver good customer outcomes."
He said Kiwibank would start contacting customers who are due payments under the agreement shortly and customers do not need to do anything before then.