A host of former Morrison government ministers are likely to be called before the robodebt royal commission.
While the social services and human services ministers at the time the illegal scheme was established - Scott Morrison and Marise Payne respectively - are already scheduled to front hearings next week, senior counsel assisting the commission Justin Greggery KC said the inquiry's scope would widen.
It means former human services ministers Stuart Robert, Alan Tudge and Michael Keenan and former social services ministers Christian Porter, Dan Tehan and Paul Fletcher could be in the firing line.
Mr Gregg said the ministers would be called in a subsequent hearing block. The next block of public hearings are set for January 23 to February 3.
Ms Payne will give evidence next Tuesday before Mr Morrison takes the stand on Wednesday.
"The evidence they are likely to give, like much of the evidence given in the first public hearing, is anticipated to be information which was not in the public domain prior to the commencement of this commission," Mr Gregerry told the commission.
"Their evidence should complete the body of evidence in respect of budget matters, policy and legal considerations in 2015."
Robodebt was initiated under the former Liberal-National government and falsely accused welfare recipients of owing money.
Automated debt notices were issued by a process called income averaging, which compared people's reported income with tax office figures.
The commission is investigating how the scheme, which operated between 2015 and 2020, went ahead despite government departments knowing the debt calculation method was unlawful.
Services Australia's Jason McNamara, who worked in the debt division during the scheme, is presenting evidence on Monday.
The royal commission continues.
© AAP 2022