ING Direct Australia lifted profit 6 per cent in 2015 to $314.7 million as it gained new customers and wrote more mortgages.
Profit growth at the country's sixth biggest mortgage lender is lower than in 2014 when it rose 9.4 per cent  to $297 million because of funding costs. 
Funding costs for all lenders have been rising again since the middle of 2015. This has been offset by interest rate rises. Most banks did this in   November, but ING did not raise rates until   January.
Transaction account customers in ING's Orange Everyday - which pays no interest but doesn't charge fees - account rose 47 per cent in calendar 2015 to 418,079 and its total mortgage book rose 2.8 per cent to $39.8 billion. The bank's total loan book stood at $43 billion, a $1 billion increase since 2014.
Total deposits rose $900 million or 2.8 per cent. APRA figures say they stood at $33.3 billion in   December. The ING savings maximiser deposits rose by 2.8 billion, or 9.9 per cent.
"Our brand is successfully evolving from being a savings champion to becoming the main bank for our customers' needs," chief executive Vaughn Richtor said in a statement. Mr Richtor, who retires in   June, said a third of the growth in customers stemmed from personal recommendations.
Several years ago the bank changed strategy to become a "main bank" for its customers rather an online savings account.
As well as the Orange Everyday account, it has sold about $7 billion in "white label" mortgages written by ING, but branded with other lenders. Mr Richtor said the bank had largely completed the loan sales and its ING branded mortgages rose by $3.8 billion, or 10.8 per cent in the year.
The founder of ING Direct in Australia, Mr Richtor will leave ING after almost two decades with the company in Australia, India and South East Asia.
"I am immensely proud of the business and what has been achieved since our launch in 1999," he said.
"Our business model challenged the way in which Australians did their banking and, while some doubted we would succeed, the provision of value for money products and exceptional customer service has proved a winning formula."