'We need to look at this' - Finance expert suspicious as Aussie banks rake in $5 billion from Kiwis

A finance expert has signalled his suspicion at the "enormous" profit the big four Australian banks are making off New Zealanders, indicating a royal commission into our banking sector may be needed.

Head of KiwiSaver provider Simplicity Sam Stubbs says the Aussie banks are making over $5 billion in profit after tax annually off New Zealanders, $1000 per person, but it's unclear why it's so large.

Mr Stubbs said he was unsure if Kiwis were bing ripped off by the banks, but said a royal commission into the sector like that undertaken in Australia could uncover similar malpractice in New Zealand.

"In Australia a whole lot of people were saying we don't need a royal commission, we don't need it. Actually when they had the royal commission, everyone's apologised from the Prime Minister down and said 'boy we needed this earlier'," Mr Stubbs said.

"I hope the politicians in New Zealand don't make the same mistake of delaying and delaying this, because with a sector that's making that much money, and so important to the financial health of all New Zealanders, we need to have a look.

Data has actually shown the big four Australian banks are making more money out of Kiwis than Australians, and they are 26 per cent more profitable in New Zealand than at home.

"We need to have a really good look and just make sure this industry is just behaving properly and appropriately," Mr Stubbs said.

"That profit number indicates that it might not be, let's have a look."

Mr Stubbs said a royal inquiry in the New Zealand banking sector would achieve two "amazing" things.

You would get banking chief executives before oath, unable to lie because it's a criminal offence - a condition that exposed several new scandals in Australia.

And, you would provide whistle blowers like bank tellers would be provided name protection and confidentiality to speak candidly.

But Mr Stubbs says the New Zealand banking sector is already lobbying and claiming it's not necessary.

"It's interesting isn't it. If the industry really had nothing to hide, wouldn't they be welcoming this commission, wouldn't they say let's get this sunlight in there, let's open the bonnet, let's have a look at what's going on.

"It's exactly the opposite of what's going on.

"They're making a lot of noise right now to not have a banking inquiry. It leads me to believe that's exactly why we should have one."

Data has revealed the big four Australian banks are making more money out of Kiwis than Australians, with the reasons unclear. Source: Breakfast