When a project is executed, the available funds are committed to various places. You create commitments by assigning purchasing documents. You post actual costs to the project. Together with the costs of apportioned orders, both of these forms of fund commitments result in what is referred to as assigned funds.

The funds overview can be regarded as passive availability control. However, the Project System also supports active availability control. The corresponding assigned funds are calculated and checked against the budget. You can find the assigned funds in the budget-bearing WBS element and in the lower-level assignable WBS elements. If certain tolerance limits are violated (shortfall in budget or budget exceeded), this can trigger various system responses (a warning, for example, or an error message). In Customizing for tolerance limits, you can specify which response is to be triggered and when.
Once activated, availability control is run for each subsequent posting in the project. The availability control performs the following tasks:
Determines the budget-bearing WBS elements (called controlling elements)
Determines the corresponding assigned funds
Checks the assigned funds against the budgets of the controlling elements.
You can find the assigned funds in the budget-bearing WBS element itself and in the lower-level assignable WBS elements (account assignment elements).