Is zakat due on a plot of land whose value is paid in installments, and when is this zakat calculated: after all installments are paid, or after the first installment, or by calculating a year for each installment? And is zakat due on the full sale price of the land including its profit, or only on the original purchase price?

Zakat is due annually on land purchased for sale, upon the completion of a full year (hawl) from the purchase price, provided its value reaches the nisab either by itself or when combined with other money or trade goods. It is appraised at the completion of the hawl, and 2.5% of its value is to be given as zakat after deducting any remaining installments or debt, unless there is other surplus wealth that can offset the debt so that the full zakat amount is paid. The zakat is calculated based on the market value of the plot at the time of paying the zakat. The price of the sold half is added to the value of the land and zakat is paid on the combined amount.