No Zakah on unlawful money earned by working in a usurious bank
30-9-2009 | IslamWeb
Question:
assalamoalykum, my sister works in a bank...an investment bank abroad. she gave her zakat to us family to distribute her zakat money amongst needy ones back home. Is it halal for us to distribute zakat money of the person who works in a bank and being my sister? jazakAllaah.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
If the entire money on which your sister wants to pay Zakah was earned by her working in a bank that deals with Riba (interest and/or usury), then this is ill-gotten money and there is no Zakah on it. However, she is obliged to get rid of it by spending it on charitable fields. Nonetheless, if she earned some of the money from her unlawful salary and some of it from other permissible income, then she should pay Zakah on the lawful money if it reaches the Nisaab (i.e. the minimum amount liable for Zakat) and a whole lunar year elapses on possessing it, and the unlawful money should be spend on charitable fields with the intention of getting rid of it. For more benefit, please refer to Fataawa 101882 and 88340.
Finally, you should advise your sister to leave her job in banks that deal with Riba and you should frighten her with the bad fate of unlawful earnings.