Australia's inquiry has uncovered a range of bad behaviour, including billing customers for services they didn't get, charging dead clients, paying staff bribes for loan referrals that shouldn't have been offered and lying to regulators.
Four of our biggest banks are owned by the Australians - ANZ, ASB, Westpac and BNZ - and they're being closely watched by authorities.
"We are very, very embedded in these banks, looking at their governance, looking at their consumer care, looking at their remediation efforts for bank complaints - that work is necessary," Reserve Bank Governor Adrian Orr told Newshub Nation on Saturday.
"At the end of that work, we may be able to say, 'Now is a royal commission necessary or not?'"
Ten banks were asked to explain their practices, and all wrote back - some with "big essays".
"They've had a lot of practice from years and years - I think there's been 55 investigations in Australia on different practices. So we've got a pretty clear guide as to where we now need to lift the lid and see, 'Well, they said this; is it real? Show us how it happened in practice.'"
Mr Orr isn't taking their explanations as gospel.
"We need to be talking to staff, to customers, to chairs of the boards, and that's what we'll be doing over the next few months."
A major area of interest is how staff are incentivised to sell products - a common problem noted in Australia.
"In some cases, that is clearly a conflict of interests if they have to sell more and more products to people who don't need them."
He doesn't expect any inquiry to find "widespread" misbehaviour, but says it's hard to tell just yet.
"I don't know if we just complain less or if it's buried more."
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