All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If the remaining amount reaches the Nisaab (minimum amount liable for Zakah) and a whole lunar year elapses over it, then, in principle, Zakah must be paid on it. However, debt prevents Zakah on hidden wealth, among which is cash money [and gold and silver] provided that the debtor does not have other assets that he may consider in return for the debt.
The Fiqh Encyclopedia reads: “The scholars who said that the debt makes the Zakah unobligatory on its amount in the Zakatable money, most of them conditioned that the person who pays the Zakah does not have what to pay his debt with except the amount on which Zakah is due. This means that if he has other (non-Zakatable) assets that are surplus beyond his basic needs, then he should consider it in return for the debt so that the Zakatable money would be debt-free and he pays Zakah on it.”
It appears to us that you have assets that you may consider in return for the debt, for example, the property that you purchased and you intend to rent is considered as surplus beyond your basic need of housing, so you should consider it in return for the debt that you have to pay and hence you have to pay the Zakah on the money that you have at hand. For more benefit, please refer to Fatwa 116828.
Allaah Knows best.