Answer
Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
It is not allowed to work with such a program that deals with interest-based system. You should not also leave your job; instead, you can leave that part to a non-Muslim colleague.
In his response to your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
You certainly do not expect me to say that it is OK to install a program that is used exclusively to apply for an interest-based loan. This is not OK, it is rather haram. This does not mean that you should leave your job as most of its functions are within the permissible range.
I suggest that you should have this part be done by a non-Muslim colleague. I understand that working in any Western country may expose you to such Shari`ah violation.
Please, keep always your effort to avoid the haram as much as you can and seek help from Allah to be always obedient of His commands. Keep istighfar (seeking Allah’s forgiveness) and sadaqah (charity) which always remedy minor sins.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.