Incorporated Engineers normally operate within a relatively well-defined technical environment, and undertake a wide range of functions and responsibilities. They are often specialists in the theory and practice of a particular branch of engineering technology or engineering-related technology, and in its application, adaptation and management in a variety of contexts. Their expertise lies in familiarity with its current state of development and its most recent applications. Within their specialist field, their expertise may be at a high level, and fully equivalent to that of a competent engineer; and they are expected to carry wide-ranging responsibilities for stakeholder interactions, for system integration, and for synthesising overall approaches to complex situations and complex engineering problems.

The work of Incorporated Engineers combines the need for a strong grasp of practical situations and applications, with the intellectual challenge of keeping abreast of leading-edge developments in their particular field. For this purpose they need a strong understanding of scientific and engineering principles and a well-developed capacity for analysis. The work of technologists is most often concerned with applying current and emerging technologies, often in new contexts; or with the application of established principles in the development of new practice. They may also contribute to the advancement of particular technologies.

Certain Incorporated Engineer qualifications include an emphasis on technical management as well as grounding in a particular area of technology. Technical management is seen as an appropriate field of specialisation in itself, and many technologists build their career paths in this direction. Examples of such specialisation include product development for manufacturing, manufacturing management, mine management, and management and maintenance of processing plants, complex building services, or testing laboratories.

Persons may also be recognized as Incorporated Engineers who hold degrees in fields related to engineering, and who have developed expertise and experience in applying their knowledge in conjunction with engineering work. Examples might be in geology and geo-techniques, information technology and software development, mining, biomedical technology, optical communications, renewable energy systems, agriculture, and so on.

The competencies of Incorporated Engineers equip them to approve and certify many technical operations such as calibration and testing regimes, compliance with performance-based criteria for fire safety, and design of components and sub-systems and of installations such as building services in circumstances that do not call for significant new development. Such certification should be fully acceptable in the public domain and should not require further endorsement by other practitioners perceived to be more highly qualified.