Is a SWMS a legal requirement?
Yes, a SWMS is a legal requirement before any high risk construction work (HRCW) starts. Under the model WHS Regulations (r.299), which apply in every state and territory except Victoria, the business doing the work must prepare a SWMS, or make sure one has already been prepared, before the HRCW begins. In Victoria the same duty sits in the Occupational Health and Safety Regulations 2017. A SWMS is not required for construction work that is not HRCW, but the risks still have to be managed.
Source: Work Health and Safety Regulation 2011 (Qld), r.299 (model WHS Regulations as adopted)