To solve the problem of the system not preventing their project managers from exceeding their budgets, you have to activate availability control in the assigned budget profile and define the tolerance limits in customizing. The budget profile is a parameter that defines the basic settings for budgeting in your project, such as whether availability control is active or not. The tolerance limits are values that specify how much deviation from the budget is allowed before the system issues warnings or error messages. Reference:https://help.sap.com/doc/0f069b2e08b748f1b480d4c8b46c3c49/100/en-US/6a7a9f0a6e421014e10000000a174cb4.html