بسم الله الرحمن الرحيم
Q: What is the ruling on working in an interest based bank?
A: Employment therein is prohibited because it can either be aiding in usury (ribaa), and if that’s the case then he (the employee) is included in the specific curse which is authentically attributed to the Prophet -sallahu alayhi wa salaam- where he said, “Surely Allah curses usury and he who mandates it, its witnesses, and its scribe (he who writes or types a contract that has therein usury). He said they are all the same.” If this is not the case then perhaps he is pleased with this (type of) work and approves of it. Thus it is not permissible to work in a place that indulges in usury.
As for depositing your money in such (a bank) out of necessity, there is no problem in that regard if you can’t find a safe place (to store your money) besides these banks. In this case there is no problem with the condition that one does not indulge in usury, as to do so is prohibited.
Translated by Najeeb Al Anjelesi
Source: فقه و فتاوى البيوع