If you are added to a project by an organization then you can record times & expenses on the project. However, only insofar as the project budget is not exceeded. If the budget of the project has been used up, the system does not accept any further time records. A good reason to record your times on a daily basis ;-)
You can see the details of the project at any time. By default, you cannot see the project budget in absolute terms. However, a progress bar appears showing how much budget has already been used as a percentage.
Every project has a budget! Team members can book times & expenses on projects. It is not possible to overbook a project. If 100% of the budget is reached, the system doesn't accept any more time records & expenses.
Of course you can create notifications for the budget. A notification contains a certain limit and a receiver. Let's say you want to get an email notification if the project budget reached 75%. In that case you could create a notification for your self. You could also create a 80% notification for your customer. That way the customer automatically gets notified as soon the project budget jumps above 80%!