With the Residential Apartment Buildings Act coming into effect on 1 September 2020, developers of any residential apartment projects that will finish before 28 February 2021 will be required to give notice to the Office of the Building Commissioner no later than 14 September 2020. 

If the initial project application was done via the NSW planning portal, then the notice should also be submitted via the portal. If it was not, the application form is here.