Taxes are immoral because the government uses force to collect their taxes. They reserve the right to imprison you if you don't pay your taxes, and reserve the right to kill you if you fight for your freedom. If another person did this we'd call it theft and convict them of a crime, but since it's the government they get special treatment.
I smell the stench of libertarianism.
If you hold that way about taxes, then you also hold like that about any law, since government can enforce it at the point of a gun. Too many unpaid parking tickets? The law will be looking for you.
Yes, the gov't gets special treatment. When gov't does something it is fundamentally different from a private person doing it.
So go ahead and suggest that all laws are fundamentally immoral since they ultimately rely on force.