These three costs catch out almost every first-time buyer, because they are separate from the price of the car and they work differently in every state.
Registration ("rego")
The fee that makes a car legal to drive on public roads, paid to your state or territory road authority. It is usually charged annually, with six-month and quarterly options in many states. The amount depends on things like vehicle type, weight, engine size and sometimes where you live.
Registration also generally requires proof the car is roadworthy once it reaches a certain age — a safety inspection report in New South Wales, a roadworthy or safety certificate in other states. Requirements differ, so check with your own road authority.
CTP insurance
Compulsory Third Party insurance covers people injured in an accident. It is compulsory and no car can be registered without it. The important difference: in New South Wales you buy it separately as a green slip from an insurer before you can register, while in most other states it is included in the registration bill. It does not cover damage to any vehicle — that is what your separate car insurance is for.
Stamp duty
A one-off state tax paid when a vehicle is transferred into your name. It is normally calculated as a percentage of the purchase price or market value, whichever is higher, and the rate rises in steps for more expensive cars. Several states apply different rates based on emissions or offer concessions for low and zero-emission vehicles.
Because rates and thresholds vary by state and are adjusted from time to time, use your state revenue office's online calculator to get an exact figure before you commit.
Transferring the registration
After a private sale, the transfer usually has to be lodged within a set period — commonly 14 days — and late transfers attract penalties. The seller should also notify the authority that they have sold the vehicle, so they are not liable for tolls or fines afterwards. If you buy from a dealer, they normally handle the transfer for you.
Moving interstate
If you move to another state, you generally have a limited time to re-register the vehicle there, which can involve an inspection and paying that state's duty. Factor it in before a move.