Welcome to day one of what is expected to be yet another gruelling Senate estimates, and the first since the May federal election.

Officials from Infrastructure, Climate Change and the Attorney-General's departments are up first today, before staff from Prime Minister and Cabinet appear later in the morning.

Thanks to Monday's public holiday, this week of sitting will be packed into just four days.

A recent flurry of secretarial appointments and shuffles means there will be familiar faces in new roles, and some new ones entirely.

Former Finance secretary Jenny Wilkinson will appear for the first time in her new role as Treasury secretary after she succeeded Steven Kennedy, who will front senators as head of the Department of the Prime Minister and Cabinet .

Ms Wilkinson's successor

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