Substantial Authority: What Actually Counts in Tax Research

Clients increasingly show up with tax positions backed by blog posts, podcasts, social media, and AI, but how much of that actually counts? Jeremy walks through the closed list of sources the regulations recognize as authority, from the Code and Treasury regulations to court cases and revenue rulings, and explains why IRS publications, form instructions, and even other tax professionals’ opinions don’t make the cut. He also covers how to weigh supporting and contrary authorities against each other, and why that matters for the Section 6662 substantial understatement penalty.