Is Zakat obligatory on 75% of an employee's income saved in usurious banks?

It is not permissible to deposit money in interest-based banks except in cases of extreme necessity, and provided that no Islamic bank is available. In such a case, the money should only be placed in a current account, not a savings account. Anyone who deposited their money in a savings account out of ignorance or error must dispose of the interest (riba) by spending it on charitable causes and repenting to Allah. Zakat is obligatory on the principal amount of the money if it reaches the nisab and a full year has passed over it, at a rate of 2.5%.