The Co-operative Bank's profit has increased 24 percent to $8.9 million in its third year operation as a registered bank.

It will be returning $1.8 million to its customers as a rebate.

Chief Executive Bruce McLachlan says they'll be getting between $10 and nearly $600.

"We realise that's not huge numbers today, but the point that we're making is the trajectory that we're on, we're increasing the rebates materially each year."

He says net profit before rebates and tax in the year to March was $13.4 million - an increase of 31 percent.

"That's up basically on the back of growth in customers, growth in balance sheet and also it's been a favourable economic environment for banks over the last year, so our bad debt levels are also very low."

He says just under 100,000 customers will receive a rebate.