Your 'maximum top up' is the amount remaining in your account before reaching your limit of $999, you can find this amount by going to card>top up>Bank Transfer
You may notice that this balance does not always match what you see in your available balance. For example, you have a $300 balance and should be able to top up $699, but instead you can only top up $400, this is because you still have $299 in pending transactions remaining.
Pending transactions are purchases made on your card that have not cleared yet, they happen most often while overseas but can also occur for a number of different reasons like when buying things online, or using prepaid petrol pumps. They can remain on your card for up to 10 business days so don't panic, but just remember that this will effect your total account balance and stop you from topping up to the total account limit until they are clear.
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