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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
You are obliged to pay Zakah on all the money that you possess and which you are preparing for purchasing a land, or for other purposes, if it reaches the Nisaab (minimum amount liable for Zakah) and a whole lunar year elapses over it while in your possession.
The Nisaab is the equivalent of nearly 85 grams of pure gold or the equivalent of nearly 595 grams of pure silver.
As regards the land which you purchased with the intention of building on it, then you are not obliged to pay Zakah on it as it is not considered as tradable commodities. With regard to what you may inherit from your father, you do not have to pay Zakah on it because it is not yet in your possession.
Therefore, if your father had gifted you some of this land and you possessed it and you had the intention when possessing it that you will use it for trade, or that you will purchase in the future a land and intend to use it for trade, then, in this case, you should evaluate it when a whole lunar year elapses over it and then you must pay 2.5% of its value as Zakah.
Concerning the gift that has not yet come into your possession, then you are not obliged to pay Zakah on it (as you do not own it).
Allaah Knows best.