"The deal was he was getting paid $10,000 to basically walk into a meeting, throw his card on the table and speak of his experience," Daniel Simon Hausmann told Barrett's NSW Supreme Court trial on Monday.

Hausman says he outlined the plan to Barrett, paying him $2000 in cash upfront, over breakfast in a Newtown cafe in January 2017.

The targets of the extortion were the masterminds of an alleged $105 million tax fraud scheme, one of whom was the son of a then-senior tax official.

"Mr Barrett was talking about what a great story it would be," the property developer said.

A third man at the breakfast, Daniel Rostankovski, was friends with Hausman and controller of the dummy directors supposedly used in the scheme to use payroll companies to avoid tax.

He was to attend the meeting with Barrett and the alleged tax fraud's masterminds, in which the journalist would discuss his years of reporting, including roles as a producer at 60 Minutes and Channel Seven.

"We explained to him that because Rostankovski had control of these (directors) et cetera, that we were looking for him to provide a threat of exposure so that we could leverage out of the meeting a financial gain for us."

His lawyer, who is yet to cross-examine Hausman, has argued the property developer is manipulative and a giver of "many, many statements" about the Plutus Payroll scandal.

Clive Steirn SC said Hausman also had an ongoing inducement to lie after receiving a sentence discount in exchange for giving evidence at Barrett's trial.

Hausman on Monday said he couldn't recall how Barrett responded to the plan but "he accepted it".

"I remember Steve said he was on board and his words were 'you've got a tiger by the tail', I remember he said that," Hausman said.

Barrett kept expressing his astonishment at who was involved, leading Hausman to say Barrett could do what he wanted with it "after we're done, when I tell you".

The jury has heard Barrett met with the alleged Plutus masterminds on February 1, laid out his credentials, mentioned a "very serious story I want to investigate", and raised the possibility of interviewing then-treasurer Scott Morrison about it.

Soon after that conversation, Barrett left the room and Rostankovski demanded the masterminds pay $5 million.

Hausman told the trial he and Rostankovski had agreed the blackmail demand would be $5 million, long before the Newtown cafe meeting.

But he couldn't recall if that figure - or any figure of significance - was relayed to Barrett.

Hausman is expected to resume his evidence on Tuesday.

Australian Associated Press