No were on a US Treasury coin is the word "note". It is not issued as debt. It is not the property of the Federal Reserve. Just like US Treasury Notes, coins cannot be used as bank reserves, just like US Treasury Notes they are not elastic.
My understanding is, just like US Treasury Notes, they are not subject to the Federal Income Tax since you are note using the private property of the Federal Reserve subject to excise.
I have heard but cannot verify that the source of the Personal Deduction in Federal Income tax is a generalized way that the IRS reconciles that we use coins and they have no taxing authority. (Can someone confirm? IRS documentation?)
To align with the momentum that this thread has taken, Treasury Coins are also fiat and they are not backed by substance (though I believe that nickels are being hoarded because their metal content is worth more than their denominated value) and what does that mean with regards to the being a token of credit from the Treasury.
I understand that like Redeemed Currency, with coins we are not endorsing private credit, we are not subject to tax or Hypothecation in their use, how do we reconcile just weights and measure on all these forms of money that are substantiated by fiat only?