Cost budgeting is a tool to estimate the costs or necessary efforts for projects, work packages or activities in project management. Cost budgeting includes the estimation of costs, setting a fixed budget, and managing and controlling the actual costs (compared to the estimated ones). The costs then have to be allocated to the activities or work packages in a project. A carefully implemented schedule and resource plan enables a more precise cost budgeting. Changes to the cost plan should be made in the following cases: