The compliance paperwork
In Victoria, plumbing and gas work has to be done by someone licensed or registered with the Victorian Building Authority (VBA). The VBA is the state regulator for plumbers.
For regulated work, the plumber lodges a Certificate of Compliance with the VBA and gives you a copy. It's your record that the work was done to the standards by a licensed person. Keep it with your house papers, because buyers, insurers and inspectors can ask for it later.
Not every job needs one. A tap washer doesn't, for example. We tell you up front if yours does, and it's included in the quote.
You can check any plumber's licence on the VBA's public register. Ours would show as VBA licence L-00000, which is a placeholder here because Bluestone isn't a real business.