Background for my question - my sisters and I were homeschooled for high school. 2 or 3 times a year, someone from the Education Department would come out and check on our work, see what level we were at, and just generally make sure we were learning and not slacking off, lol.

Does that happen for unschooling? If so, how do you ensure your child is up to a certain level?
Yeah, it's still just a style of home education so the same rules apply. It's different in every state though, e.g in Qld you need to send in a plan at the start of each year for them to approve. At the end of the year you send a report and work samples showing how the child has progressed. So if you unschool it can be a bit tricky depending on the child but people still make it work.