The Australian Taxation Office has moved swiftly to try and instigate a wholesale restructure of its mammoth Service Delivery Group (SDG), as the revenue agency tries to consolidate and simplify overlapping or duplicated functions in its main customer-facing arm amid a big push to call in debts.

Tax employees and unions this week moved into the formal consultation phase for the giant administrative overhaul, which has officially kicked off just weeks after new commissioner of…