Car accident lawyer, Tumbi Umbi: who was at fault?

The insurer that decides fault will not have been there. It relies on what people recorded at the time. So record what you can: the time, the weather, the road surface, the lane markings and the direction each vehicle was travelling. If a witness stopped, ask whether they'll give their name. A note written that evening is worth more than a memory months later.

• The lane each vehicle was in, and any lane change
• Where each car came to rest, photographed before moving if safe
• Whether you and your passengers wore seatbelts
• Weather, light and the road surface at the time

Most people hurt in a car crash can claim statutory benefits regardless of fault, covering weekly payments and reasonable and necessary treatment. Fault matters most for the lump sum. Common law damages are only possible if another driver was at fault, you were not mostly at fault, and your injury is more than a threshold injury. So a fault finding against you can close off damages even while benefits are paid.

A seatbelt argument is the classic example. If the insurer says your injuries were worse because you weren't belted in, it may reduce what you receive. The percentage isn't set by a formula. It's argued on the evidence, including medical opinion about how each injury happened, which makes it worth checking rather than simply accepting.

A passenger isn't driving, so a passenger is rarely found at fault for the crash itself. The claim goes to the CTP insurer of whichever vehicle was at fault. If your own driver caused it, that's the Green Slip of the car you were in, even when the driver is a friend or family member. The insurer responds to the claim, not the driver personally.

Children in the car are in a special position. Whoever caused the crash, a child aged 16 or under at the time can keep receiving treatment and care for as long as they need it. Usually a parent or guardian lodges the claim for them. Fault can still matter for other entitlements, so keep the police record with the child's medical records.

Chain collisions are where fault gets complicated. The driver who started it may carry most of the blame, but a driver behind who was following too closely can share it. Each vehicle has its own Green Slip insurer. Your task is to record every vehicle involved and the order of the impacts; the insurers' task is to sort out which of them responds.

The police event number is often the thread that ties a multi-vehicle crash together. It links the drivers, the vehicles and any statements taken at the scene. Keep it with your registration notes. CTP Assist, a free SIRA service on 1300 656 919, can help identify an insurer when you're unsure, though it won't decide fault for you.

Fault is decided on evidence, not on who sounds more certain. The usual pieces are the police event number and any police record, photos of where the cars stopped, the damage to each vehicle, dashcam footage and independent witnesses. No single piece is always decisive. Together they usually show what happened, even when the drivers tell different stories.

The police event number links your claim to the official record of the crash. The insurer can use it to check who was involved and what was reported. It's worth getting even if the crash seemed minor and police didn't attend, because a record made close to the time is harder to dispute than one pieced together later.

• Dashcam footage, saved as the original file
• Independent witnesses' names and numbers
• Your own written account from the first days
• Photos of signals, signs and lane markings

A fault finding isn't final just because the insurer has made it. Most insurer decisions can go to internal review, generally within 28 days of receiving the decision, and then to the Personal Injury Commission. Before you accept a finding that you were mostly at fault, have someone look at whether the evidence supports it, because so much turns on that line.