do i need a roadworthy to transfer registration

Short answer: maybe—because Australia loves a bit of admin roulette.

VIC and QLD require a Roadworthy/Safety Certificate to transfer a registered car in a private sale. In the ACT, an inspection is usually needed when transferring ownership if the vehicle is over 6 years old. In NSW, SA, WA, TAS and NT, you generally don’t need a roadworthy just to transfer current rego, but you will if the rego’s expired, there’s a defect notice, or you’re re‑registering/interstate. You’ll still need the usual paperwork—proof of identity, transfer form and duty—so don’t rock up with only optimism and a pen. If in doubt, check your state or territory authority before money changes hands; rules and fees do move around.