Department officials and senators will return to Parliament House for the third day of Senate estimates, with four new committees ready to scrutinise departments.

Up first this morning is the Department of Health, Disability and Ageing , with secretary Blair Comley expected to appear, as well as the Department of the Treasury, including new secretary Jenny Wilkinson .

The Department of Employment and Workplace Relations and the Department of Defence are also gearing up for several hours of questioning.

Follow the live blog below as we bring you all the updates from day three:

Day two of estimates brought with it revelations about the Optus triple-zero outages, while Home Affairs secretary Stephanie Foster clarified reports of women and children returning to Australia from Syria.

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