Zakat is compulsory on all net Zakatable assets which includes all money, regardless if it is kept at home or deposited in a bank account. Thus, Zakat is also binding upon the amount one had in their bank account on their Zakat day. After tracing the balance of the bank account on their Zakat day, one can give 2.5% of bank balance as Zakat.

And Allah knows best!

Mufti Faraz Adam