You can't complete this form without it.
If you don't know the registration number of the vehicle at fault, you might be able to get it from the police if the incident was reported to them or police attended at the time. Contact the Police Assistance Line on 131 444.
You need to take all 'reasonable' steps to find the rego number, but if you can't you can still make a claim. Call CTP Assist on 1300 656 919 for more information.
If you believe that you are at fault, you will need to provide the registration number of the vehicle you were driving.
If you are at-fault you can still make a claim with your insurer.