Is zakat obligatory on a deposit from which withdrawals are made, approximately, when needed?

Money deposited in banks and the profits generated therefrom are subject to Zakat if they reach the nisab (minimum threshold) and a hawl (one lunar year) has passed, provided that these profits are lawful. However, if the profits are unlawful, Zakat is not obligatory on them, and they must be disposed of by spending them on charitable causes with the intention of getting rid of unlawful money, not with the intention of giving charity. It is not permissible to deposit money in interest-based banks except in cases of extreme necessity. Withdrawing from the deposit does not prevent the obligation of Zakat if the remaining amount reaches the nisab and a hawl has passed over it.