The amount of home loans that have been extended based on "factually inaccurate" information is estimated to have reached $500 billion, according to an updated study by investment bank UBS.
The broker said that its latest survey of over 900 mortgage applications originated over the last 12 months revealed that about one third of home loans contained information that was not accurate.
Given the "rising level of misstatement" of many years, UBS said it estimated $500 billion of home loans were "liar loans", the researchers, Jonathan Mott, Rachel Bentzvelen and George Tharenou wrote.
"While household debt levels, elevated house prices and subdued income growth are well known, these finding suggest mortgagors are more stretched than the banks believe, implying losses in a downturn could be larger than the banks anticipate.
The UBS report suggested more borrowers were lying by under-representing their expenses and living costs.
Borrowers were also over-stating income and assets and understating loans.
Mortgage & Finance Association of Australia chief executive Mike Fenton said the findings were "wrong" and were based on an incorrect calculation.