How is the zakat calculated for money saved to buy an apartment, when a portion has been paid as a down payment, another portion will be paid later, and a portion has been received from an association but a hawl (lunar year) has not yet passed on it?

Zakat is obligatory on money if a lunar year has passed since it reached the nisab (minimum threshold) (85 grams of gold, or 595 grams of silver). The obligatory amount is one-quarter of one-tenth (2.5%). Zakat is not obligatory on money that has not completed a full year, or on money that has been paid as an installment. The amount that will be paid before its year is complete is not subject to zakat. However, if a year passes on it before it is paid, then zakat becomes obligatory on it if it reaches the nisab. The remaining payment in cash is subject to zakat if it reaches the nisab and a year has passed on it; otherwise, it is not.