We originally charged a lifetime fee to the Year 12 students, so an exit-fee model. However, a few years ago we moved to an entry-fee model, where the students are charged upon enrolment. The entry-fee is higher than the exit fee, however, a portion of the amount is given to the school for the current students. The reasoning behind this is to provide benefit to the students prior to them becoming alumni. For example, we support a Targeted Tuition Programme that is run throughout the year that provides exam skills sessions, tutoring in subjects, etc. We start marketing the alumni association as providing benefits and opportunities before the students leave, hoping that it will encourage them to stay engaged.
I hope that helps!
Scotch College (Perth)