Whoever has wealth which has reached the Nisab and a year has passed over it, and also has a debt which engrosses the Nisab or renders the remaining wealth after repaying the debt, less than the Nisab, does not pay any Zakat. This is for example if one who possesses 1,000 Dinars and owes 1,000 Dinars, or one who possesses 40 gold Dinars and indebted by 30 gold Dinars, there is no Zakat upon him in these two cases as he does not own the Nisab. From Nafi from ibn ‘Umar who said: The Messenger of Allah (saw) said: “If a person has 1,000 Dirhams and is in debt of 1,000 Dirhams, then there is no Zakat upon him.”
When the wealth after paying the debt reaches the Nisab, then Zakat is obligatory upon him due to what was narrated by As-Saib b. Yazid who said: I heard Uthman b. Affan saying: “This is the month of your Zakat. Whoever has a debt should pay it so that you give the Zakat on your wealth.” In another narration: “Whoever has a debt should pay it off and pay Zakat on his remaining wealth.” He said this in the presence of the Sahabah who did not deny it, thus indicating their consensus (Ijma’a).
Where a person is a creditor of a debt to a non-deferring rich person who is able to repay it at any time, it is obliged upon him to pay Zakat on that debt when a year passes over it. ‘Umar ibn Al-Khattab said: “When Sadaqah becomes due, count your debts and what you have as one whole then pay its Zakat.” Uthman b. Affan said: “Sadaqah is obliged upon the debt which you could collect from the debtor if you want, and that debt which is on someone who delays repayment and you leave it due to shyness or as a favour; in it is Sadaqah.” Ibn ‘Umar said: “On each of your debts in which you expect repayment you must pay Zakat whenever the year passes over it.”
However, where the debt is owed by a poor person in hard circumstances, or a deferring rich person, it is not obliged upon the creditor to pay its Zakat until it has been repaid. After it has been repaid he gives all that was obliged upon him over the years. Regarding a doubtful debt i.e. one in which the creditor is not sure if it will be resolved or not. Ali said: “If he is honest let him pay the Zakat once it has been restored for the period.” Ibn Abbas said regarding debts: “If you don’t expect to receive it, don’t pay its Zakat until you get it. When you receive it, pay all that is upon it.”