Once you have activated EZ-Reload for your EZ-Link, the auto top-up will occur when the remaining value in your EZ-Link is insufficient for your next payment transaction at any train gate, bus device or retail acceptance terminal.
For example, if you have activated EZ-Reload on your EZ-Link for $30.00, the remaining stored value in your EZ-Link is $2.50 on and the journey costs $2.70:
When you tap your EZ-Link at a train gate, the auto top-up will occur due to the minimum required value of $3.00 for entering a train gate. So the new balance in your EZ-Link that will be displayed when you exit will be $29.80.
When you tap your EZ-Link on a bus reader (e.g. Express Bus service), the auto top-up will occur when you exit based on the calculation that the cost for the total journey is more than the balance value in the card. Hence, the new value displayed on the bus exit reader will be $29.80.