To receive event notifications when a customers’ unbilled usage balances reach, go above, or go below a percentage of thresholds that you specified, it is recommended to configure the Unbilled Usage Threshold Adjustment Percentage setting.
For example, if you set the unbilled usage balance threshold for various customers to $100 and you specify that you want to receive event notifications when 80% of that threshold is reached, then you will receive event notifications when their unbilled usage balance reaches, goes above, or goes below $80.