Is zakat obligatory on the amount that was deducted from the price of the shop, which is the original debt I lent to someone?

Zakat is obligatory on a debt every year if the debtor is wealthy and willing to pay. It is to be paid either upon receiving the debt or along with the zakat on one's wealth. However, if the debtor is a procrastinator or is in straitened circumstances, zakat is not obligatory until the debt is received, and it is paid only once for the year of receipt, as a facilitation for the owner and the one in straitened circumstances. If the debtor is not a procrastinator, the creditor must pay zakat for all the past years. And if the debtor was in straitened circumstances and the debt was collected from him, then the creditor must pay zakat for one year.