Lower or eliminate income tax for 6 months? That would give everyone at least a 20% raise and more then that for others. People would spend money, invest and save. It would probably cost the same or less than the money that has been spent trying to fix the economy already.
The federal government doesn't have any money. They are just printing it out of thin air(computerized) as it is. So, they are actually taxing us right now through diluting the dollar. The goverment could only lower taxes right now if they would make tough choices and cut spending significantly. They would need to close all of our military bases, cancel medicare, social security, etc. It ain't gonna happen. So, they just print.