"We know that our customers need to first look after themselves, their families and their businesses and that financial flexibility means different things to different people," said Healy.
BNZ said both business and personal customers could apply to access temporary overdraft facilities or credit limit increases, restructure business loans without incurring fees, suspend loan payments on business and home loans and access term deposits early, and without penalty.
Kiwibank said it would offer affected customers a three month overdraft of up to $1000 or an increase to $1000 for existing overdraft or revolving credit facilities at standard rates to assist with unexpected expenses as a direct result of the event.
It will also offer a simplified application process and no overdraft fees, early access to term deposits and faster access for hardship assistance for home loans.
An ASB spokeswoman said the bank had been working with customers affected by the flooding to assess their individual needs and would offer support as our customers assess the damage.
"We encourage any impacted customers to call us on 0800 803 804 to discuss their circumstance and how we can tailor appropriate support for them."