Is it permissible to work in a riba-based bank in which the people in charge are trying to turn it into an Islamic bank?
Question

I have been offered a job in a bank that has both Islamic and commercial branches, and the interview was for a job in a commercial bank, but when I hinted to them that I wanted to work in the Islamic branch, I was told that they are in the process of turning the entire bank into an Islamic bank. One of the people there was an expert in Islamic banking, and he said that he was there to seek two rewards: the reward for turning the bank into an Islamic one and the reward for working in an Islamic bank.
My question has to do with the period prior to the change: is it permissible for me to work in a commercial bank until it becomes an Islamic bank? Is my work regarded as rewardable, because I am playing a role in the foundation of an Islamic bank, and that is based on my experience in Islamic banking, and also my administrative post. Please note that I am currently working in an Islamic bank, but I am not happy because there are serious and unIslamic practices in it that overstep the mark.
Praise be to Allah.Firstly: 
it is not permissible to work in commercial banks which do not pay attention to the rulings of Islamic sharee‘ah in their transactions or in some of them, because that comes under the heading of haraam work and of cooperating in sin and transgression, as those banks base many of their transactions on riba (usury), gambling and other kinds of transactions that are contrary to sharee‘ah. 
Please see the answer to questions no. 104930 and 153084
Secondly: 
If the Islamic bank is really operating in accordance with the rulings of Islamic sharee‘ah, then it is permissible to deal with it and work in the bank. 
But if these banks are Islamic in name only, and they deal with riba and other haraam transactions, then dealing with them is haraam even if they call themselves Islamic banks, because what matters is actual facts, not mere appearances, and what matters is the reality of things, not what they are called. 
Please see the answer to question no. 47651 .
Thirdly: 
if the bank has Islamic branches that pay attention to shar‘i rulings in their operations, and other branches that do not pay attention to shar‘i rulings, it is permissible to work in the Islamic branches but not in others, if they really do adhere to Islamic rulings and they have their own system that is not subject to the general system of the riba-based bank, and it is supervised by a trustworthy sharee‘ah board. 
Please see the answer to question no. 118294
Fourthly: 
With regard to working in banks that have started to Islamise, if these banks are in the process of actually changing and getting rid of their former riba-based accounts and transactions, and moving towards Islamisation in a serious manner, and correcting their procedures, and the work does not involve starting or renewing haraam dealings, then there is nothing wrong with working for it and being paid for that work, if it is done with a good intention and sincerely for the sake of Allah, on condition that the bank should have a trustworthy sharee‘ah board to supervise the Islamisation process. That board should also supervise the bank’s operations in the future, and the administration of the bank should adhere to the decisions of the trustworthy board. 
But if the actual transformation process is slow and is not serious, and the bank is still involved with new riba-based dealings, and it is waiting for the right time, or the right circumstances, or the right time to repent… Then it is not permissible to work in this bank, because the haraam dealings are still going on, with no excuse. In order to attain forgiveness of what has passed, Allah, may He be exalted, has stipulated that the accountable person should refrain from committing new acts of disobedience as He, may He be exalted, says (interpretation of the meaning): “Say to those who have disbelieved, if they cease (from disbelief) their past will be forgiven. But if they return (thereto), then the examples of those (punished) before them have already preceded (as a warning)” [al-Anfaal 8:38]. 
Shaykh ‘Abd al-‘Azeez al-Fawzaan (may Allah preserve him) said: 
It is permissible to work in Islamic banks so long as they adhere to the guidelines set out by the sharee‘ah committees and boards. It is also permissible to work in banks that have started to change over to be Islamic banks. 
As for working in riba-based banks, it is not permissible, even if the work is in a permissible field. End quote.
And Allah knows best.