The minister responsible for robodebt ordered an independent investigation into the controversial scheme but the damning results were never shared with his department, allowing the unlawful program to continue for several years.

PricewaterhouseCoopers (PwC) was commissioned by former Human Services minister Alan Tudge to investigate the scheme in 2017, but never produced a final report after the department told them a visual presentation midway through the audit was sufficient.

PWC partner Shane West on Friday gave evidence to the royal commission into the Centrelink debt recovery scheme that recovered more than $750 million from more than 380,000 people.

After the Human Services department indicated the presentation would act as the audit’s final product, PwC ditched their investigation and never handed over a written report despite drafts being at a late stage.

It led commissioner Catherine Holmes to suggest Mr West’s evidence “challenges credulity” and said it suggested a “nod and a wink” had been given by the department to bury the report.

She said PwC’s approach to fulfilling its near-$1 million contract was “very laissez faire”.

“What was made clear to you? ‘Gosh we’re happy with the presentation you made and we don’t need any more?'” Ms Holmes asked.

“You’ve almost got it finalised, and then it’s clear a presentation you’ve given a couple of weeks earlier will fit the bill?”

Presented with an interim summary of the audit, Mr West agreed PWC had found “a lot of flaws” in the system, later adding there was “clear evidence the savings weren’t going to be achieved”.

One draft report included former senior Human Services official Jason McNamara lashing the government’s new scheme as “only caring about the money”, referring to $8 billion in budget savings via the welfare system.

“The government doesn’t care about what they do with compliance to achieve it … other than the department doing something politically silly, they don’t care,” the report quotes Mr McNamara as saying.

Mr West indicated PwC’s review wasn’t to rely on information the department had documented to date, which Ms Holmes characterised as a “mistrust in the work they’d done to date”.

“There was a view what the department had documented … might not have been 100 per cent accurate,” Mr West said.

The unlawful scheme involved using annual tax office data to calculate fortnightly earnings and automatically issue welfare debt notices.

A fourth block of hearings is due to start on February 20.

– AAP