With Project you can control when costs accrue in tasks and their assignments. This setting can override the automatic generation of the costs associated with resource usage (which are by default prorated) and place cost realization at the beginning or end of the task. This might be used for alignment when the costs are realized by billing systems and it can help you manage cash flow in your project. You can define the cost accrual methods for resource costs and the fixed costs for tasks.
What do you want to do?
Change how resource costs are accrued
On the View tab, in the Resource Views group, choose Resource Sheet.
(In Project 2007, choose View > Resource Sheet.)
In the Resource Name field, select a resource.
Right-click to select Information, and on the Resource Information dialog, choose the Costs tab.
(In Project 2007, choose Resource Information, and then choose the Costs tab.)
In the Cost accrual list, select the accrual method you want.
Caution: We recommend that the resource cost accrual setting be made when a resource is created, and then not modified. Changes may move planned and actual costs, which could change actual costs
Note: Per-use resource costs are incurred at the start or finish of an assignment, not via the prorated accrual method.
Tip: A safe way to change an incorrectly set accrual value is to create and assign a new resource and transfer remaining costs from the old to the new resource.
Change the fixed-cost accrual method for new tasks
Choose File > Options > Schedule.
(In Project 2007, choose Tools > Options > Calculation.)
Under Calculations options for this project, in the Default fixed cost accrual list, select the accrual method that you want to apply to all new tasks in this project.
Note: If you want to apply this accrual method to all future projects, next to Calculations options for this project, select All New Projects.
Change the fixed-cost accrual method for existing tasks
On the View tab, in the Resource Views group, choose Other Views, and then select More Views.
(In Project 2007, choose View > More Views.)
In the More Views dialog box, select Task Sheet, and then choose Apply.
In the Data group, choose the arrow on Tables, and then choose Cost.
In the Fixed Cost Accrual field, select from the list an accrual method that you want to apply to each task.
Note: This cost setting affects only how fixed costs are accrued.