The government collects tax for their own purposes and objectives, whereas the khums is a tax legislated in the Sharia taken on the yearly profits that remains after deducting the yearly expenses. The khums is legislated for specific goals which the Holy Legislator intended. Those goals are totally different from the uses of the government imposed taxes. It is natural then for the duty-bound individual to be obligated by the Sharia to pay khums regardless of whether he is paying other taxes or not.
