I think I get it now.
IRC says substantial authority as a minimum & more likely than not for tax shelters.
So always apply the IRC rules first. Then…
Edit, “if a taxing authority has no written standards for preparing or signing tax returns, or if its standards are lower, then two AICPA standards apply”
Those two are 1) Realistic possibility (33% likelihood) OR 2) A reasonable basis (20-33%) and that position is disclosed to the IRS for further review
And this reminds me, the hierarchy of tax law is:
Supreme Court –> IRC –> Treasury Dpt information –> everything else? I know I have it written somewhere but I can't seem to find it.
FAR - 86
REG - 83
AUD - 97
BEC -