All perfect praise be to Allah, The Lord of The Worlds; and may his blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
: Funds are either deposited as a loan in a current account or as a Mudarabah (co-partnership) in an investment account.
As regards the current account, Zakah becomes due on it once it reaches Nissab (Minimum amount liable for Zakah) and one lunar year has passed over possessing it, because it is money that has become liable for Zakah. Therefore, the owner must pay its Zakah for each lunar year: 2.5% from the amount left in his account at the end of that year. As regards the investment account, Zakah is due on it as well because it is a developing wealth.
Therefore, its Zakah is calculated separately for every lunar year: 2.5% from the amount remaining in that account at the end of that year.
However, the Zakah on the profits of that money is calculated at the end of the lunar year. And Allah knows best.