Austrian incest jailer Josef Fritzl is putting his life story up for sale to the highest bidder and hawking his property empire at bargain-basement prices in a bid to raise cash for his secret family.

Fritzl, 74, says he wants to provide "a secure future" for the incest tribe he fathered in a secret cellar beneath his home where he raped his daughter Elisabeth over a 24-year period.

Just four weeks before he stands trial for the crimes, Fritzl has been declared bankrupt by authorities winding down his $A6.5 million property rental empire.

Lawyer Walter Anzboeck has been assigned to act as liquidator for Fritzl's insolvent real estate businesses. He said on Sunday: "Mr Fritzl is ready to open up and reveal everything about his motives and the background of the case if it helps to care for his family."

Mr Anzboeck said he was aware this was a "very sensitive matter", and pledged that he would "do nothing without checking with the court, the family, the creditors and the victims' lawyer".

Austria has rules against paying criminals cash for their stories, but Mr Anzboeck said no money would go to Fritzl but only to his daughter and the six surviving incest children she bore him in her subterranean prison.

Fritzl is believed to be asking for in excess of $A1 million for his sordid story.