Is zakat obligatory on the amount saved to purchase an apartment before its construction is complete, and what about the amount paid as a down payment?

Zakat (definition) must be paid on money saved for building a house, for marriage, or for other needs, if it reaches the nisab (definition) (minimum threshold) and a hawl (full lunar year) passes over it, due to the generality of the Sharia (definition) proofs. As for placing money in usurious banks, it is not permissible except in cases of extreme necessity and without interest. Zakat is not waived by the intention of marriage, paying off a debt, or purchasing real estate; rather, it increases and purifies wealth. Zakat is obligatory on money saved for building if it reaches nisab on its own or when combined with other cash or trade goods. The preponderant opinion is that a deferred debt does not waive zakat on saved money if it reaches the nisab. As for what was paid as a down payment for purchasing a house, there is no zakat on it because it has left one's possession.