To make things easier, here's an overview of the main moments you missed during Tuesday's estimates hearings:

Secretary Pezzullo has rejected the UN Special Rapporteur on Torture's assessment that Australia runs an "inhumane" refugee policy and practices indefinite detention.

"We just don't agree with her characterisation," Mr Pezzullo said.

"Everyone is the subject of constant review under our status resolution processes and whether they need to be breached or whether they need to be extended in terms of, of their visa condition is something that's actively considered with us.

"We don't just lock people up and forget about them."

The head of the Australian Electoral Commission, Tom Rogers, said that we are seeing an "extraordinary enrollment rate" ahead of the referendum.

"This referendum will have the most complete electoral roll in Australia's history, with an extraordinary enrollment rate sitting at 97.2 per cent and we continue to focus on underrepresented cohorts," Mr Rogers said in his opening statement.

Mr Rogers also said the electoral commission has already noticed an increase in disinformation and threatening commentary ahead of the referendum.

Greens senator Larissa Waters questioned Climate Change Authority chair Grant King's ties to the gas industry, and asked if any other country has a former fossil fuel executive as chair of an independent climate agency.

Mr King is a former chief executive of gas giant Origin Energy.

Progressive think tank The Australia Institute sent climate change minister Chris Bowen a letter last week, urging him to review the appointment of Climate Change Authority chair Grant King due conflict of interest concerns.

Ms Waters also asked whether Climate Change Authority representatives had held meetings with the gas industry, and asked about a recent declaration from a CCA board member who revealed they did work for Santos last year.

The Albanese government has hit back against claims from the Coalition that regional funding programs are at risk under its 90-day infrastructure pipeline review.

Nationals senator Bridget McKenzie said estimates hearings have revealed that the future of the Roads to Recovery program, the Bridges Renewal Program, Black Spot Program, and Heavy Vehicle Safety and Productivity Program is in jeopardy.

Catherine King, Minister for Regional Development, accused the Coalition of running a "fear campaign" on Tuesday afternoon.

"It is outright scaremongering to suggest that the future of long-standing programs is in jeopardy because the government is looking to see what improvements could be made to provide more flexibility to local councils and lessen any unnecessary administrative burden," Ms King said in a statement.

Labor senator and committee chair Nita Green earlier cracked the whip after senators "descended into nonsense" in front of ASIO.

Liberal senator Gerard Rennick kicked off his questions to agency head Mike Burgess on trans women after Greens senator David Shoebridge earlier asked about anti-trans groups and neo Nazis crossing paths.

Agriculture Minister Murray Watt interjected after Senator Rennick put the question to him as well.

"We're here to answer serious questions about real threats that are facing the country at the moment, which Mr Burgess has talked about, I'm not going to provide you assistance to continue fighting your culture wars that you've been doing," Senator Watt said back.

The bickering between senators on all sides continued before Senator Green called a quits.