How is the tax system immoral?
Are you really serious?
How about the redistribution of income and wealth for starters? Taking from one to give to another at point of a gun, if necessary, if the threat of imprisonment isn't enough to get you to comply, sounds pretty immoral to me.
Government can only do what has been delegated to it. We cannot delegate powers that aren't lawfully ours. If it's illegal for me or you to do it, it's out of the proper bounds of government to do.
Is that immoral enough?