Getting a report and consent is a fairly common process and is requested by the building surveyor for most projects. In short, this is required if your design is seeking some sort of variation from the standard building regulations. For example, if you want to reduce a front setback or build on the boundary, and instances similar to these.
In the case of our own house we want to keep the new dwelling exactly where the existing (to be demolished) one is. But the existing house sits further forward then our neighbours. So, we need to apply for a report and consent to keep the reduced front set back.
Another silly, but often required report and consent may be needed for daylight access to habitable rooms. These windows need a 1m clear to sky opening. However, often, when you build relatively close to a boundary, say you might be 1.2m away from the boundary and have a 600mm eave you only have 600mm clear to the sky. So, for instance if you have a splashback window in your kitchen, that faces the side. Even though you have big open windows and doors facing the rear, with plenty of light coming in, your splashback window at the side would not comply with the regulations.
In my opinion, this is a very silly rule. The alternative is often to have no eaves at all. Which is the reason why most of the cheap / standard developments never have any eaves. However, I do think it is better to have the eaves (especially if it is part of a design intent) and apply for the report and consent. Especially when it comes to eaves they almost always get approved; it is just a bit annoying as it requires a fee with council. Usually something between $250 – $350 per report and consent…
Here is a link to the practice note from the VBA
https://www.vba.vic.gov.au/__data/assets/pdf_file/0005/99392/PN-57-Report-and-Consent.pdf
It does make sense to give your project a thorough review before applying for the building permit. So that you can make an informed decision whether you want to apply for a report and consent or rather try to amend the design slightly.