Praise be to Allah.
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) said:
If this building which was sold after one year was bought to be sold (for profit), then zakaah is due on it, on the price for which it was sold. Zakaah should be paid if one full hijri year has passed between the time when its owner decided to sell it and the sale took place. But if he did not buy it in order to sell it (for a profit), rather he no longer had any need of the house or property, and he wanted to sell it, but it took so long because he could not find anyone to buy it, then there is no zakaah due on its price, but whatever he keeps of its price after paying off his debts, once one full hijri year has passed he should pay zakaah on it, but if he spends it before the year has passed then there is no zakaah due.
In conclusion: If this property is bought for trade, then he has to pay zakaah on it when one full hijri year has passed from the time when he decided to sell it, even if it has not yet been one year since he sold it. If he did not intend to trade it, rather he no longer had any need of it but he could not find a purchaser until after a year had passed, then he does not have to pay zakaah on its price, rather he has to pay zakaah on the money he receives, when a full year has passed. And Allaah is the Source of strength.