The audit report also reveals that during negotiations over a key agreement with French company Naval Group in 2018,the federal government's hand-picked advisory group floated the idea of walking away from the contract with the French shipbuilder.
The Naval Shipbuilding Advisory Board told Defence that it should consider whether proceeding with the project was in the national interest"even if negotiations succeeded"with the Strategic Partnering Agreement.
In February last year,Naval Group asked for a 15-month extension in the design phase to minimise delays down the track during construction,pushing out the design completion date from July 2022 to September 2023.
Defence and Naval Group then settled on the nine-month extension.
Defence has so far spent $396 million on the design phase of the project,which makes up nearly half of the total cost of the project to date.
While Defence had established the arrangements necessary for the effective administration of the program to deliver the 12 new submarines,the audit raised concern about the nine-month delay.
The report says a three-year delay in the Future submarine program would create a capability gap for Australia’s critical submarine capability,with the Collins-class submarines needing upgrading before the French-built replacements are ready.