As the former champion on the Subchapter S-Corporation issue at the IRS, Mike explores how the IRS looks at a business valuation focusing on tax affecting Subchapter S-Corps. With his books “Business Appraisals and the IRS” (May 2013) and “Valuing Interests in S-Corps” (June 2013) current material is provided on this topic. Key items related to factual development are presented. Five major models are discussed including Fannon, Grabowski, Mercer, Treharne and Van Vleet. The major US Tax Court cases are explored. This information is presented to assist you as a business appraiser to make good decisions based on the facts in your case. Specific recommendations are suggested when providing an S-Corp valuation for various purposes.