Very well, you're not aiding and abetting.
You're also not personally stealing from me. (in fact, since I think you're in another country you're not stealing from me at all, but that's beside the point) What you are doing is delegating your desire to steal from me (figuratively speaking) to a group of people. So a better description of what is going on would be conspiracy.
Myrkul, to be perfectly accurate (assuming we're going to apply physics here), our statist friend hasn't actually stolen from anybody. The State thru some delegating body (taxing facility) has taken/stolen/coerced money from the many. These are the thieves we should pursue. He personally hasn't actually stolen anything (he applied no force to that effect) from anybody. However, he is in possession of stolen property, which if it could be determined (difficult if the state refuses to disclose who they stole it from), could then be returned to you (the taxed/plundered). Now, if he were to refuse to return the stolen property, he would then qualify as a thief and could be prosecuted forthwith.
If we stick to the physics, we can punish the right individuals. Unfortunately, the State protects it's own. To wit, they give special privilege and license to the few, to plunder the many. They have a license to steal, protected by a greater collective force than you personally can produce in self defense, hence you yield to the plunderer because you fear for your life (or you value it more than your stolen property). This is why Sweden wouldn't dare try to tax Americans (or the reverse) because we know our "State" would protect us from such a seige.
Unfortunately, many of us don't stand up to the State (local) and refuse to be robbed. Shame, apathy breeds the seeds of destruction.