Is zakat obligatory on money saved for building a house, while also having a debt to an Islamic bank to finance the purchase of the land?

If you have other money in excess of your needs, it will be deducted to offset your debt. Zakat then becomes obligatory on the wealth that reaches the nisab upon the completion of its hawl (lunar year). However, if you do not have other money, the debt will be deducted from the amount. If what remains reaches the nisab, then Zakat is due on it upon the completion of its hawl; otherwise, there is no Zakat.