Christian Porter, Alan Tudge and Rachelle Miller to give evidence

Miller handled media inquiries about the scheme, pointing to an Ombudsman’s report on the program that had been drafted with the involvement of the now-defunct department of human services.

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Comment has been sought from Tudge. Porter and Miller declined to comment.

Miller tweeted on Tuesday: “Just when you think 2023 is the year to move on from politics…”

Miller went public in November 2020 on the ABC’s Four Corners program to reveal she had an affair with Tudge while he was her boss.

Tudge was stood down from the front bench in December 2021 after Miller publicly alleged he was emotionally abusive and on one occasion physically abusive while the pair were travelling together for work.

Tudge denies the allegations and was subjected to two inquiries. The first, conducted by law firm Sparke Helmore, was commissioned by the Morrison government but did not find sufficient evidence to substantiate allegations of inappropriate behaviour.

The second inquiry, by Vivienne Thom, a former inspector-general of intelligence, found Tudge had not breached ministerial standards, but Miller did not participate in that inquiry.

The royal commission last month heard from former prime minister Scott Morrison, who was social services minister at the outset of the robo-debt scheme.

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Morrison told the commission he was never advised the scheme was unlawful before he signed off on it, and said it was “unthinkable” that his department did not pass on crucial legal advice.

Morrison, who was responsible for taking the proposal to cabinet in 2015, said it was inconceivable top bureaucrats wouldn’t have told him of the legal issues involved in calculating welfare debts by income averaging, before he admitted under questioning his belief in the legitimacy of the crackdown had been proven wrong.

Liberal senator Marise Payne, who was human services minister at the time the program was being devised, also fronted the commission hearings in December and confirmed that she signed and annotated an executive minute in early 2015 that said the proposal would need “legislative and/or policy changes” but said she didn’t know why the advice had later fallen “off the radar”.

The third tranche of hearings will run from January 23 to February 3.

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