Is Zakat obligatory on an apartment that was bought for a son to be used as a residence or for sale?

The rented apartment is not subject to zakat on its value as long as it was not intended for trade. Zakat is due on its rent if a year has passed over it and it has reached the nisab (which is equivalent to 85 grams of gold), and the amount of zakat is a quarter of a tenth (2.5%). Gifting the apartment to a minor son is valid, and the father acts on his behalf in taking possession of it.