Now, you can absolutely argue that the taxes being imposed or suggested are unnecessarily high, or perhaps that most of the money being levied is being squandered on things that those paying see no benefit from (which perhaps one could argue is theft, but that last part is crucial), and I'd not argue one bit with you in many cases. I'll be the first to say that the use of Western tax dollars in Ukraine is an absolute slap in the face for the taxpayers who see no benefit therefrom, and who had nothing to do with the coups that led to the war in the first place.
But taxation in and of itself isn't theft, any more than property, in and of itself, is theft. As long as the left and right just keep shouting "THIEF!" at each other, we don't really have any hope of getting anywhere.