To determine if a business activity is substantially related requires examining the relationship between the activities that generate income and the accomplishment of the organization's exempt purpose. Trade or business is related to exempt purposes, in the statutory sense, only when the conduct of the business activities has causal relationship to achieving exempt purposes (other than through the production of income). The causal relationship must be substantial. The activities that generate the income must contribute importantly to accomplishing the organization's exempt purposes to be substantially related.
