A Repair Certifier can only issue an LT308 for an unregistered vehicle (unless specifically requested to by NZTA), but they may provide a report for repairs on an in-service vehicle, which is sometimes requested by Warrant of Fitness Inspectors when they have concerns about repairs on a vehicle they are inspecting.
A Repair Certifier may also be employed to supervise a repair by a repairer, the vehicle owner, an insurance company, or a motor vehicle dealer in the event of a dispute.