Corruption investigators have performed a significant flip and will scrutinise senior public servants involved in the unlawful robodebt scheme.
Following a review process, the National Anti-Corruption Commission announced on Tuesday it will probe whether any of the six officials referred in the robodebt royal commission's final report engaged in corrupt conduct.
This overturns the commission's controversial June decision not to investigate the referrals, and has been welcomed by the Community and Public Sector Union as a step towards addressing a "cruel and illegal" scheme.
"For years, the architects of robodebt have walked away without consequence, while the people they harmed have been left to pick up the pieces. That is unacceptable," CPSU national secretary Melissa Donnelly said.
"The lives of countless Australians were devastated by this scheme.
"This is an important moment in the ongoing push for accountability, and we continue to hope that it delivers the transparency, justice and accountability so many Australians have been waiting for."
The watchdog did not reveal reasons for starting an investigation, noting that could prejudice the process.
But in October, the National Anti-Corruption Commission Inspector Gail Furness found the commission's head Paul Brereton engaged in misconduct as he had ties with one of the six in question but did not adequately recuse himself from the watchdog's decision.
Mr Brereton and the other deputy commissioners involved in the original decision will not participate in the investigation.
Between 2016 and 2019, the former coalition government's robodebt scheme recovered more than $750 million from almost 400,000 people.
Many welfare recipients were falsely accused of owing the government money and the program was linked to several suicides.
Greens senator David Shoebridge welcomed the investigation by the watchdog.
"This is a chance for justice for the thousands of people across the country whose lives and families were shattered by robodebt," he said.
"Today's announcement is a clear rejection of NACC's previous decision, in which Commissioner Brereton was deeply involved, to ignore this scandal."
The previous decision of the watchdog not to investigate the referrals had led to calls for the commissioner to step aside from the role.
Senator Shoebridge said the commissioner needed to be trusted by Australians.
"This trust is undermined by the continued presence of Commissioner Brereton," he said.
