Advanced Estate Planning with S Corporations: Tax Structuring, Trust Design, and Succession Strategies for Closely Held Business Owners

S corporations account for more than 6 million annual tax filings in the United States, yet the Subchapter S eligibility rules under IRC §1361 remain among the most unforgiving traps in estate planning. A single ineligible shareholder, a misfiled QSST election, or a trust provision that inadvertently creates a second class of stock collapses the S election with no path to retroactive cure. As the $14 trillion privately held business wealth transfer accelerates through 2026 and attorneys face clients simultaneously planning for death, succession, and generational transfer, the margin for drafting error has never been thinner. Estate planners, business counsel, and trust attorneys who rely on legacy documents without S corporationspecific review are already exposed. This program maps the full compliance architecture across both the planning and post-death phases, covering QSST, ESBT, and grantor trust selection criteria; buy-sell agreement coordination with estate documents; and the mandatory IRC §754 and post-mortem election deadlines governing the 90-day window after a shareholder dies, equipping attorneys to audit existing plans, restructure defective trust provisions, and execute succession transitions without triggering termination.