According to the PMBOK® Guide (6th Edition), the Control Costs process is the process of monitoring the status of the project to update the project costs and managing changes to the cost baseline.

When a change is made to the project budget during the execution of the project—even with the project manager ' s approval—it falls under the monitoring and controlling domain. This process ensures that all change requests are processed in a timely manner and that the budget remains aligned with the actual work performed.

Key responsibilities within Control Costs include:

Influencing the factors that create changes to the authorized cost baseline.

Ensuring that all change requests are acted upon through the Perform Integrated Change Control process.

Managing the actual changes when they occur.

Ensuring that cost overruns do not exceed the authorized funding (both periodic and total).

Analysis of Distractors:

A (Manage Cost Plan): This is not a formal PMI process. The document that describes how costs will be managed is the Cost Management Plan, which is an output of the Plan Cost Management process.

B (Estimate Costs): This is a planning process focused on developing an approximation of the monetary resources needed to complete project activities. It happens before a budget is established.

C (Determine Budget): This is the process of aggregating the estimated costs of individual activities or work packages to establish an authorized cost baseline. Once the budget is determined and the project moves into execution, any further adjustments to that budget are handled by Control Costs.

Key Document Reference: Section 7.4 of the PMBOK® Guide states that " Control Costs " involves informing the appropriate stakeholders of all approved changes and associated costs. It is the mechanism through which the budget is maintained and adjusted throughout the project life cycle.