Voluntary. Riiiiight. And I'm Donald Duck. Sure, you "volunteer" to pay your taxes, or you can "volunteer" to have your wages garnished, "volunteer" to have tax liens filed against you, "volunteer" to have your bank account(s) siezed, "volunteer" to be harassed and eventually hauled into court and prosecuted, and "volunteer" to be thrown in prison. Or, you can pony up the vigorish and avoid all of that.