Is Zakat obligatory on a sum of money deposited in an Islamic bank, the profits of which are used to cover part of the housing rent, with additional assistance from the mother to cover the remaining expenses, knowing that this sum is insufficient to purchase an apartment and that the questioner is divorced and supports her children?

If the amount reaches the nisab and a full hawl (lunar year) has passed, then it is obligatory to pay its zakat and the zakat on its profits. Zakat is not waived on the pretext of desiring to purchase an apartment. Zakat is a blessing for wealth and a means of its growth, and it is forbidden to use trickery to avoid it. A Muslim should hasten to pay it with a willing heart, and Allah will compensate him with something better.