Program service activity, tuition and fees, contribute importantly to the college's exempt purposes by providing educational services to students at less than the aggregate cost of these services. Such activity is the primary purpose for which the college was formed. All other revenue of the college, such as auxiliary enterprises, are essential components of the college's desire to provide a Christian education to its students. Since these activities are substantially related, and contribute importantly, to the accomplishment of the college's exempt purposes, the net income is not required to be reported on Form 990-T.