If you are using the Transaction feature and the Transaction Total and Remaining Budget fields then you have the ability to trigger a Notification to a relevant person to inform that your Budget Threshold has been reached.

This function uses our Automation feature where you can set up a Rule for example, when your Budget is within 10% or £100 then notify a particular person via a Task so they can Action if required.

Please refer to the article for Automation Actions that will detail how this particular Rule can be created.