I have sums of money owed to me by some people, but I am not sure if I will get these sums back, for some of them are insolvent, and others are procrastinating. Moreover, there are others whom I do not know their circumstances. Should Zakat be paid on these sums and how should I calculate it?
Answer: The debts due on solvent people that you can receive upon demand, Zakat is due on them every year after the elapse of a full Hawl (one lunar year calculated from the time a property reaches the minimum amount upon which Zakat is due) just like the money that you are in full possession of.
As for the debts due on insolvent people, who are more than likely going to be unable to pay back the debt, no Zakat will be due on them until the debt is repaid. Thus, upon receiving it, the person should pay Zakat due on it after the passing of a Hawl from the time of receipt, according to the correct scholarly opinion.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.