Is zakat obligatory on a borrowed sum, a hawl (lunar year) having passed over it, knowing that it is deducted from the salary monthly?

If the borrowed money reaches the nisab (threshold), scholars differ regarding its zakat:

The Shafi'is hold that debt is not deducted from zakat at all. Therefore, zakat becomes obligatory on the money if it reaches the nisab and a full year has passed over it. The majority of scholars hold that debt is deducted from zakat. If, after deducting the debt, the remaining money reaches the nisab and a full year has passed over it, then zakat becomes obligatory; otherwise, it does not. The Maliki school holds that if the debtor possesses an asset for acquisition that he does not need, he should use it to offset the debt, and thus the debt is not deducted from the zakatable money. Otherwise, the debt is deducted from the zakatable money.