Q: is it allowed to not pay full taxes? If we can prove that the money is not used for the interest of the people? (Email)
A: One must pay what is due. This is the agreement we have made by choosing to be part of a given country. One can use the services of professionals to attain the best financial representation so long as the laws of the land are not violated.
You can challenge the law through legals avenues that could allow for greater tax reform resulting in lower taxes. Not going through legal channels would remain an injustice towards the system. Work within the system to improve the system, not against the system.
Allah Certainly Knows Best.