When I negotiate a check I make a general reservation of rights: "ALL RIGHTS RESERVED" and a specific reservation immediately thereunder: "I DEMAND LAWFUL MONEY". These reservations are consistent with the UCC and apply to any negotiable instrument.

I do not expect to receive "Lawful money" but that is not the point. The point is I have not waived my right to lawful money. Because I have not waived my right to lawful money I have not accepted obligations of the United States as a measure of the value for the transaction. Consequently there is no taxable event until I receive something of value for the transaction.

I don't know if lawful money is exempt from taxation or not. But who cares? I do not accept FRNs as the measure of the transaction because they are only obligations of the United States!