What is the amount of zakat due on a sum of EGP 67,500, to which profits of EGP 32,500 have been added, knowing that this amount was designated for purchasing a marital home, and that the date of its receipt dates back to January 1, 2013?

The determining factor for Zakat (definition) is complete ownership of the wealth, its reaching the nisab (definition), and the passing of a full year (hawl) on it, regardless of the intention behind owning it. If the wealth is invested, then it is obligatory to pay 2.5% (a quarter of a tenth) on both the principal and the profit for each year that has passed without Zakat being paid. If the amount is unknown, it should be estimated to the best of one's judgment to ensure acquittal of one's duty.