Methods including the behavioural science of welfare recipients was touted by department officials as a way to claw back debt during the early stages of the robodebt scheme, the royal commission has heard.
The former general manager in the Department of Human Services, Mark Withnell, told the commission on Friday he tried to tell senior officials within the department the use of averaging to calculate debt would not be supported by other agencies overseeing the scheme.
Mr Withnell said despite his comments, the then-deputy secretary of the department, Malisa Golightly, still wanted the scheme to go ahead.
"I spent some time talking with Ms Golightly to convince her that the use of income averaging would not be supported by (the Department of Social Services), and that it was probably inappropriate to continue with that.
"She was very keen on the measures still proceeding."
The former manager said he suggested alternatives to reach out to those on welfare who the department suspected of having debts to the government such as behavioural science.
"The critical issue for me was about getting people to reconcile the information (about the debt)," Mr Withnell said.
"That reconciliation of information would still allow us to proceed, but that using the ATO data in the way that had been suggested would not be acceptable to DSS and wasn't an acceptable process."
When questioned why estimates for budget savings being recovered would be the same even if averaging wasn't used, Mr Withnell said he did not know.
He indicated it would be up to the Department of Social Services to calculate the costings.
The royal commission is examining how the scheme was allowed to continue despite legal advice showing the use of averaging ATO income data was unlawful.
The commission was shown documents made during the pilot stage of the scheme, which showed 60 per cent of people provided with debt notices did not contact government departments about the notice.
"These customers have debts raised based on the match (pay as you go) data, and are sent a debt notice," the document said.
A Victorian legal aid lawyer, a barrister, the deputy CEO of Services Australia and a person affected by the illegal debt-raising scheme will give evidence later on Friday.
Three former social service ministers are also set to front the hearing next week.
Stuart Robert and Michael Keenan will front hearings for the first time while Marise Payne will reappear, having previously given evidence in December.
The royal commission is set to hand down its report on June 30 after the deadline was extended when an extra 100,000 documents were produced.
