Investors may have acquired units of EnerVest Diversified Income Trust at various times and prices, particularly those who have exercised Rights Offerings over the years.  Considering the requirement to reduce the cost base of the investment by the return of capital payments received, calculating an accurate adjusted cost base upon disposition can be challenging.  You may wish to consider the services of ACB Tracking Inc., at www.acbtracking.ca, providers of an adjusted cost base calculator developed expressly for this purpose.