How is Zakat calculated on money paid to the questioner's father for the purchase of a plot of land in installments?

Zakat is not obligatory on purchased land unless it is intended for trade. In that case, its value is assessed, and Zakat of one-quarter of one-tenth (2.5%) is due upon the completion of a full year from its purchase price. As for savings from one's salary, Zakat becomes obligatory on them if they reach the nisab (minimum threshold) and a full year has passed, and its amount is one-quarter of one-tenth (2.5%). It is permissible to deduct debt from the Zakatable wealth if there are no other assets exceeding one's basic needs.