A ‘bus’ is defined as a motor vehicle which seats more than 12 adults (including the driver).
If the vehicle has 12 or fewer seats, including the driver, then any children under the age of 7 years must use an appropriate child restraint or booster seat.
If the bus has more than 12 seating positions, including the driver, the children are not required to use child restraints or booster seats.
VicRoads recommends that child restraints and booster seats are used in buses where possible. As a minimum the children should use the seat belts provided.