Cost estimation and control is vital to a project’s success. For this reason a major part of any project is the cost management plan. It can be found within, inside, or be presented as part of a project management plan. A Cost Management Plan is a document which will outline the criteria and activities which must be carried out as part of project management. A Cost Management Plan provides both input cost estimates, the amount of money being spent, and cost output estimates, which is the amount of money estimated to be received. It will provide the planning and structure necessary to control the costs of the project, keeping them within the limits of your budget. The exact nature of a Cost management Plan may very greatly. They can be formal and precisely worded or written very casually. Some can be highly detailed while others take on a broader aspect that looks more at the big picture. More experienced project management will have less need for a clearly defined cost management plan, though will still be required to review it and follow it to the letter. The exact nature of the cost management plan is dependent on the interests and needs of the project stakeholders.
This term is defined in the 3rd and the 4th edition of the PMBOK.