Is Zakat obligatory on a sum of money lent by a person to be used as a down payment for purchasing an apartment, knowing that the intention to purchase was not present at the time of lending? And how is it to be paid in Zakat if the purchase is not made and the loan is recovered after a year or more?

If the money paid is in the form of a loan, then zakat is obligatory upon the owner of the money. He may pay zakat on it along with his other wealth or defer the zakat until he receives the money back. However, if the money is part of the price of an apartment being purchased, then it has left the possession of the payer, and no zakat is due on it from him. If the contract is annulled and the money is returned to him, he starts a new zakat year (hawl) for it. The contract for purchasing an apartment in this manner is "istisna' (manufacturing contract)." If it fulfills the Sharia conditions, such as knowledge of the price, the object of sale, and the timeframe, then the contract is valid, and zakat is obligatory as previously mentioned. Otherwise, the contract is void, and the money remains the property of its owner, and zakat is obligatory upon him for it.