An apparatus and a method for deactivating an airbag in a motor vehicle with at least one vehicle seat, to which a child seat placed on the seat can be fastened. A device is provided for deactivating an airbag located in front when the child seat is mounted. In order to allow such a device to be retrofitted simply and economically even in existing mass-produced vehicles, the device is formed by a tongue additionally mounted on the child seat and a latch connected in an active relationship with a central triggering unit. The airbag is deactivated by inserting the tongue into the latch and is reactivated by releasing the connection. For this purpose, the latch has an integrated sensor connected by a lead to the central triggering unit. In order to increase the certainty that the airbag will be shut off when the child seat is mounted, the sensor is made redundant.