Mike presents his perspective having led a team at the IRS on valuing subchapter S corporations and discusses the inconsistencies in application at the IRS. Subchapter S corporation tax history and issues are provided to introduce the subject matter. Issues related to Built in Capital Gain (BIG) tax are discussed and when a valuation is needed for subchapter S corporations. A look at six pertinent court cases associated with “tax affecting” are explored including a more detailed look at the most recent court case on this issue. Five of the most popular models used for “tax affecting” are introduced and discussed. Given this material the practitioner is asked whether they believe they should make an adjustment for Subchapter S valuations (“tax affecting”) or not considering the various risks of this factually intense and well litigated issue. Finally, Mike presents his personal perspective on the issue and invites attendees to share their views.