Fallacy:
I consider taxes a good deal: what I pay is worth what I get. (Implied: Most people do, and so taxes are voluntary.)
Sometime the Oliver Wendell Holmes quote, "I like to pay taxes. With them I buy civilization." is used.
Response:
Merely because you agree—and I suspect even you don't agree to every tax, all of the time—doesn't mean taxes are voluntary. It only takes one person at one time to disagree with one tax or regulation imposed on them to make them involuntary (just as one counterexample will invalidate a purported mathematical proof). And I definitely don't agree. TaxationIsExtortion.