Income concepts can be viewed as a pyramid. As one moves from the broad notion of psychic income through the foundation and accounting concepts of income to the legal concept, the interpretation of income continually narrows. More and more items are excluded from income as one progresses from one discipline to the next and in doing so one moves further away from the ‘ideal’ taxation target. Taxation is based on the legal concept of income – the concept farthest removed from the ‘ideal’ on the income pyramid.