Consultancy involves a person either contracting privately or through his or her office to provide professional advice in return for financial remuneration either to the individual or to the company.

Consultancy services are one particular type of service delivered under a contract for services. They are distinguished from other contracts by the nature of the work performed.

Typically, the term consultancy services is used to describe the application of expert professional skills to: investigate or diagnose a defined issue or problem; carry out defined research, reviews or evaluations; or provide independent advice, information or creative solutions to assist the agency in management decision-making. A consultancy contract will typically define the nature, purpose and duration of the task to be performed but does not detail the manner in which the task is to be performed.