I mean, the US doesn't recognize that I have any authority to tax anyone, and I have no leverage to get people to pay up. But could I declare that I am President of the Shadow Government, or Divine Lord of Reddit, or otherwise go full sovereign citizen, and start asking people to pay additional taxes to me? Note that I'm not talking about pretending to be the IRS, but rather representing that I personally, or my organization, has the (self-granted) authority to levy taxes.

Most likely outcome seems to be nobody paying me, and second most likely outcome seems to be losing in small claims court when someone sues for their money back on the basis of my not having given them any consideration in exchange for the payment.

However, I'm interested in the potential for a fraud case. I'd obviously be telling people that they "must" pay me, but in this case the necessity is really just my personal opinion. Who is allowed to represent that actions or payments are mandatory?

I'm also interested in whether there's a particular law disallowing me from soliciting payments and calling them "tax". If I structured the whole scheme as a club, told people they were members, and then started asking for "dues" to maintain their membership in good standing, I'm sure I could get away with it.