If you forfeit your copyright for the purpose of a tax right off, and to abandon your responsibilities to the work, then your work reverts to the default status

If you forfeit your copyright for the purpose of a tax right off, and to abandon your responsibilities to the work, then your work reverts to the default status (prior to any copyright law) of public domain. (And, Yes, you better make sure you have the rights to public domain every part of the work, or you don't get the right off.) If you retain ownership rights (+ responsibilities) then you don't get the tax write off. That seems pretty simple, no?