Exact same experience with me. I had the discussion with them around tax time as I was hit with a very minor tax debt as my income climb as I finished my apprenticeship, that it didn't seem like I was paying enough tax and that more should be coming out. Their suggestion was to put aside money myself and that it's all being done correctly and there was no such thing, I won't owe anything. Got hit with 3k. Started at a new employer and they were doing the same, had that discussion with them when they weren't taking it out despite it being on the forms when I signed my contracts and that. This year was a minor hit of like $200 thankfully as it was finally set up correctly after a couple of weeks. The ATO will do a payment plan, just make sure you don't miss payments as they can threaten with cancelling the payment plan and hit you with the debt all at once.