Does the zakat paid on debts before they are collected count, or must it be paid again upon collection of the debt?

Scholars have differed on the ruling of paying Zakat on a debt before it is collected. Some permitted it, while others prohibited it, which is the more cautious opinion, because Zakat is not due on it until it is collected. Therefore, paying it before it becomes due is not sufficient. Others, however, believe that Zakat becomes due on a debt upon the passing of a year (hawl), but the payment is delayed due to the inability to collect it. Thus, paying it before collection is like paying Zakat on fruits before harvesting, after their ripeness becomes apparent. It is advisable to adopt the more cautious opinion, which is to pay Zakat after collection.