WEBJul 15, 2024 · DA Form 2 – Building work details to make a development application involving building work – effective 7 February 2020. 9 Application to vary the Building Act 1975 (PDF, 177KB) or (DOCX, 68KB) – effective 1 September 2021. 11 Certificate/interim certificate of occupancy (PDF, 115KB) or (DOCX, 56KB) – effective 1 October 2020.