When changes are made to resource or role cost information, you are prompted to recalculate assignment costs, so that the correct values display for activity costs in all open projects. The Recalculate Assignment Costs command ensures that project costs reflect any updated price/unit values on activities.
For example, you should recalculate assignment costs if you change a resource's or role's price/unit and the resource/role is assigned to activities, or if a resource/role has multiple prices and the activity dates change, since the activity cost calculation is based upon the activity start date. In some cases you will be prompted to recalculate costs. You can also choose Tools, Recalculate Assignment Costs, provided you have access rights to View Resource and Role Costs/Financials, which is set at the project level. When P6 Professional is connected to a P6 EPPM database, the appropriate privilege is defined in P6.