One way to pop the country's ballooning house prices would be to force investors to pay cash, a researcher says.
Two separate pieces of research into the housing market have found easy credit is behind the rise in house prices - not immigration.
Mike Rehm from the University of Auckland's Faculty of Business has just presented his findings to the 24th Pacific Rim Real Estate Society Conference.
He said one way to deflate the market could be to force investors to use cash.
"The banks would again hate that because that's a huge element of their business but if you want to do what's right for society - you have to discourage residential investment."
Dr Rehm said immigration was not the driving force behind rising prices and raising interest rates had little impact.
"It's not as if these new immigrants are coming in and pumping up and out-bidding the locals, per se, for houses because they're really going in as renters for a period of time."
Another recent study found that Aucklanders had to save 8.8 years to save for a deposit for a house - that's worse than London's 8.5 years.