Your OBU needs to be switched on and coupled to a vehicle to receive a top-up.

Important: you need to enter your customer number, followed by your complete OBU serial number (with a space between these two references) in your payment instruction. Be aware that if you do not use the correct reference, it will take more time for the top-up amount to be loaded onto your OBU. Your customer number is found on your billing documents or in parentheses (in the top right-hand corner) just after your name on the Road User Portal.