Mike Pezzullo on full pay during investigation

Mr Pezzullo has stood aside for the duration of the APSC's investigation into leaked text messages to a Liberal powerbroker.

The leaked messages revealed Mr Pezzullo used a political back channel to two former Liberal prime ministers through powerbroker Scott Briggs to wield influence.

Mr Pezzullo's total remuneration package is $914,659.

Ms Foster's pay packet has also gone up while in the role due to higher allowances.

The new boss expressed her shock at Mr Pezzullo being stood down while the public service commissioner investigates his leaked texts.

"I want to start by acknowledging the significant shock all of us in the Home Affairs portfolio experienced ... when secretary Pezzullo was asked to step aside," Ms Foster told senators in her opening statement to a parliamentary hearing on Monday.

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She said it had been a difficult time for staff in the agency, with "sustained and distressing" media attention throughout.

She said Mr Pezzullo regularly disclosed conflicts of interest but didn't confirm whether his relationship with Mr Briggs was disclosed due to the ongoing investigation.

The public service's policy states possible conflicts of interest include political affiliations and activities.

It is not suggested the messages show corrupt or illegal conduct but public integrity advocates have alleged Mr Pezzullo overstepped the required impartial nature of heading a government department.

Ms Foster is truly in the hot seat, faced with a barrage of questions about Mr Pezzullo, whose connection to Liberal powerbroker Scott Briggs is being scrutinised by the Public Service Commission.

Labor senator Raff Ciccone has been putting questions to the acting secretary and getting nothing back.

"So any matter you're just deferring in relation to Mr Briggs and Mr Pezzullo?" he asks, after getting nothing out of Ms Foster.

"That's correct," she says.

"I am confident that when the inquiry concludes there will be appropriate clarity on what actions were and were not taken," Ms Foster says of the Public Service Commission's probe into the agency's secretary Mike Pezzullo, who has stood aside for the duration.

This is likely not the last time she's forced to address the Pezzullo matter today, but probably sums up the vibe best.

Have Home Affairs' infamous dress code requirements been scrapped?

Apparently yes, and it wasn't Ms Foster's idea.

"Quite a prescriptive dress code" was reviewed, driven by an internal conversation about maturing the culture of the organisation, officials told Greens senator Nick McKim.

The dress code has now been relaxed to focus on reminding staff to dress appropriately, and is a very general approach.

This all commenced under Mr Pezzullo, officials said.