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 obviously known that cheating is un-Islamic. Also, every Muslim is ordained to highly observe his or her income whether it is lawful (halal) or not making sure that every penny he or she earns must be from a halal way.
In his response to your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
Muslims are not allowed to cheat anyone, including the government. If we wish to work and earn our income in a lawful (halal) way, there are other lawful ways. Allah has promised to open the doors for us if we are sincere and strive for it.
So, the income he or she has earned from this work is tainted with haram. They should purify it by repentance and refraining from such practices.
Almighty Allah knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.