Kiwibank says its growth in the second half of the financial year depends largely on how competitive its rivals decide to be.
The New Zealand Post-owned bank made a profit of $25.8 million in the six months to December, an increase of 14% on the same period a year earlier.
The increase is largely due to higher interest income as its lending portfolio expanded 25% to $7 billion.
Kiwibank chief executive, Sam Knowles, says it was able to do that because its competitors' response to the financial crisis was to its advantage, as they became less competitive in the mortgage market.
But Mr Knowles says that situation was a "one off" and other banks are likely to return strongly to the market.
Kiwibank's retail deposit base grew 31% to $6.3 million, but Mr Knowles says a recent plethora of bond issues will inevitably affect bank deposits.
Mr Knowles says the bank's credit losses remain low at 0.06%.
