A former minister in charge of robodebt has denied responsibility for his department’s failure to check the legality of the scheme and said he still believed it was lawful in the face of mounting issues.

Alan Tudge, who served as human services minister between 2016 and 2017, told the royal commission examining the controversial Centrelink debt recovery program it was not his responsibility to determine whether it was legal or not.

Mr Tudge said he never asked for or saw legal advice about the robodebt scheme and the issue did not cross his mind “until I read about it in the newspaper” years later.

The ex-minister said while he did not consider the legality of robodebt, questions were raised about its fairness.

“It is unfathomable for a (department) secretary to be implementing a program which he or she would know to be unlawful. It is unfathomable,” he told the commission.

Mr Tudge said although he wasn’t responsible for ascertaining whether robodebt was legal or otherwise, he was in charge of departmental matters and accountable for its “lawful implementation”.

The scheme, which used averaging on incomes to determine debt levels, ran from 2015 to 2019, continuing to operate despite legal concerns.

It recovered more than $750 million from more than 380,000 people and several people took their own lives while being pursued for false debts.

Mr Tudge said he was aware robodebt had the potential to create debt notices to recipients that were inaccurate, having found out it was occurring in early 2017.

“I was aware that the system, even from an income averaging perspective, had the potential to create inaccuracies,” he said.

“The way the system was designed was that the onus was put on the recipients to provide the evidence of their income if – through the data-matching process – there was a discrepancy between what was self-reported.”

The former minister said he had no recollection of being “excited” about the prospect of recovering money as part of data-matching activities, despite emails between tax office staff presented to the commission stating he was.

Mr Tudge was also asked about his office’s response to media coverage of someone who died by suicide after receiving a robodebt notice.

He said language in an email from his media adviser Rachelle Miller, which criticised reporting of the suicide as a “nice start to the weekend”, was insensitive.

However, the ex-minister said the comments did not reflect his office culture about attitudes towards robodebt victims.

Mr Tudge was the third former coalition minister to appear before the inquiry.

Christian Porter, who was in charge of social services during the scheme’s operation, will give evidence on Thursday.

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