Is zakat obligatory on my sick brother's money deposited in the bank, knowing that its income is insufficient to cover his family's expenses, and is it permissible for him to take from zakat if it becomes obligatory upon him?

Zakat is obligatory on money deposited in a bank if it reaches the nisab and a full year has passed over it. Its amount is 2.5% of the principal and its profit. It is not permissible for the depositor to take zakat for himself. The inability to withdraw the money does not negate the obligation of zakat. Zakat should be paid from the profit received annually.