Corrective action refers to any activity of action that is instituted, the point of which is to alter the course of a specific task or project that may have lost focus or somehow deviated form the pre-specified direction it was intended to take. This new direction should be well-documented and should, upon execution, turn the project in a way such that it better aligns with the goals, expectations, and ultimate results laid out in the project management plan. Corrective action can be implemented at any point within the project when the project as a whole, or a specific task or tasks, have taken the project in a direction which is in conflict with the pre-determined project management. Earlier intervention traditionally is more effective as it can involve a more minor correction than later intervention, which can require a more significant alteration, which can result in more financial and time expenditures.
This term is defined in the 3rd and the 4th edition of the PMBOK.