How is Zakat calculated on an amount of money in a savings account at an Islamic bank, while having a loan from the same bank, and using the account to cover daily needs, which makes it difficult to determine the amount upon which a year has passed?

It is recommended to designate a specific day of the Hijri year—the day on which the wealth reached the nisab—for the purification (zakat) of all money annually, whether a year has passed on it or not. Debts are deducted from the zakat wealth if there are no corresponding assets. As for spending from this wealth during the year, it is more cautious for the spender to consider it from subsequent earnings. The preferred approach is to adopt the view of the Hanafis.