in my state, the rego bill is sent out 6 weeks before it's due to. i save up for the annual bill, every fortnight, so that when it comes around, i have the money ready. A financial counsellor i saw years ago, advised me to do this (save up for annual bills, as they are a known thing, not a surprise, like an unexpected car repair). i am indebted to that person for that advice, it has taken some stress off me.

you get your annual bills, add 10% (to allow for inflation), divide by 26 - and that will tell you how much you need to save up each fortnight, in order to have enough for the annual bill, when it arrives. the best time to start doing it, is when you pay your current bill. i remember it was not easy at the start, but it got easier.