Former minister Stuart Robert has told the Robodebt royal commission he takes "absolute responsibility" for the implementation for the illegal scheme.
The former government services minister has also revealed he went on television programs defending the program as a "dutiful cabinet minister", despite being aware it could be unlawful.
He gave evidence at the inquiry into the rollout of the automated welfare debt recovery scheme being held in Brisbane today.
When asked by Commissioner Catherine Holmes SC whether he took responsibility for "what the government, of which you were a part of, did?"
"Absolutely, Commissioner," Mr Robert replied.
"As a senior member of the government, I take absolute responsibility as part of cabinet solidarity for this.
"But I also take responsibility for being the minister to say: 'We have got to get advice to stop it now'."
Mr Robert discussed "holding [the] government line" in all media interviews – including one on ABC's 7.30 — despite having "personal misgivings" about Robodebt's calculation method.
"The sole use [of income averaging] could not be sufficient, it just can't," he said, adding he was not sure about the "partial" use of income averaging in relation to the debt-raising program.
"Sole use … it couldn't possibly work but just because I have a reservation does not mean I am going to go on Laura Tingle's program and say the government's policy is wrong.
"That is just not how a Westminster government operates."
He also defended his role in publicly backing the policy.
"As a cabinet minister I don't get to choose the polices I agree with or don't agree with," he told the inquiry.
He earlier said: "Ministers are required to defend the government's programs as part of cabinet solidarity regardless of if they agree with them or not".
"I have implemented many things I passionately disagree with, but I'm still required as a minister to represent them and defend them and that's what I've done here, regardless of my personal sense or belief," Mr Robert said.
He told the inquiry more questions should have been asked about Robodebt and he remained "flabbergasted" that legal advice had not been ordered sooner.
Robert says he acted to shut scheme down
Mr Robert disagreed with statements former Department of Human Services secretary Renee Leon made to the royal commission that he had been slow to stop the scheme and told her: "Legal advice is just advice."
He also denied telling Professor Leon the government would "double down" on the scheme, once he had been given legal advice it was not lawful.
Mr Robert said he had a very strong view the numbers used in Robodebt "didn't add up" but he could not tell cabinet he was not confident of the scheme without legal advice.
He said once he got the legal advice from the Australian solicitor-general that the scheme was unlawful, he acted within "two hours".
"I had it for two hours before I walked straight into the prime minister's office unannounced and put it down and said: 'We need to stop this'," Mr Robert said.
Mr Robert this morning engaged in several terse exchanges with counsel assisting Angus Scott KC, leading Commissioner Holmes to assure the MP that the barrister was "not his adversary".
It comes after the MP was asked whether he needed to be "convinced" to end Robodebt "because the [DHS] secretary [Renee Leon] perceived a lack of support from you".
"I completely reject that in the strongest possible terms," Mr Robert said.
"I asked for the [legal] advice on the 4th of July, I wanted it.
"And when they had it … they ostensibly sat on it to work out what to do.
"I also put it to you, sir, respectfully, that if that advice had been put to me then this issue could have been resolved earlier."
Commissioner Holmes interjected: "You don't need to put things to Mr Scott. He's not your adversary, he's just asking questions".
Lack of written legal advice 'unconscionable'
The Gold Coast MP instead claimed DHS had withheld advice from him for months, saying it did not appear in any written briefings to him.
Mr Robert earlier suggested Professor Leon could have committed an offence by failing to provide legal advice about the scheme to him sooner in 2019, saying a breach of her governance obligations could be "in play".
Commissioner Holmes suggested to Mr Robert the fact it was not put in writing could have been because previous evidence to the commission had alleged difficult conversations were shared with ministers orally.
"The fact that this advice could not be shared with me in writing is simply unconscionable, Ma'am," he told Commissioner Holmes.
The inquiry continues.
