All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ʻalayhi wa sallam, is His slave and Messenger.
If you bought this plot without the intention of selling it and getting a profit out of, then it is not liable for zakaah; as in case if you had bought it with the intention of building on it or for other purposes. However, if you bought it with the intention of selling it for a profit, then it is subject to zakaah regardless of its value. Do not give out zakaah based on its value at the time of purchase; rather, you should pay the zakaah based on its market value when the lunar year elapses. You should pay 2.5% of its value every year. If the value decreases or increases, the amount of the zakaah decreases or increases accordingly. For more information, please refer to fatwas 90450 and 96293.
As for your debt (the remainder of the price), according to the majority of the scholars, you should deduct it from the sum liable to zakaah. The Shaafiʻis, on the other hand, held that the debts should not be deducted from the zakaah, and this view is more prudent. The view of the Maalikis – which is the view that we adopt at our website – is that if you have surplus property (that is not intended for trade) beyond your essential needs, then you should pay zakaah on all the wealth that you own without deducting the debts, and you consider this surplus property as debt collateral. If you do not have surplus property beyond your essential needs, then you should deduct your debt from the money liable to zakaah. For more benefit, please refer to fatwa 350707.
Allah knows best.