Implement alert/notification to monitor WIP

To implement a function that can be activated on bill4time to enable an alert to be sent to the user once they reach a certain percentage of an agreed WIP (work in progress) amount on an individual matter where a fixed fee has been agreed between parties?  For example, if on an individual matter we have an agreed WIP/fixed fee amount of $10,000 we would like to activate an alert or email to be sent to the user to notify them that they are now at 10% of reaching the WIP/fixed fee amount of $10,000. This would enable the user to then request a fee uplift from the relevant party if required.