Dan Mayo is a Partner with over 25 years of professional tax experience in federal, international, and financial products taxation.
As the Lead for Withum’s National Tax Services practice, he helps businesses structure their affairs and plan transactions to minimize federal income taxes. He is experienced in mergers and acquisitions, capital markets transactions, and cross-border transactions, and he represents individuals and businesses in tax controversies with the IRS. Dan also serves as an expert witness in litigation involving tax issues.
Dan is a recognized expert in the areas of Qualified Small Business Stock (QSBS) and the Employee Retention Credit (ERC), and he co-leads Withum’s ERC Group. He keeps a pulse on federal income tax matters and upcoming legislation, and not only is he a thought leader within the Firm, but he is also an adjunct tax professor at Georgetown University Law Center, writing on all things tax and sharing best practices for minimizing taxes for businesses and HNW individuals.
Learn more about my professional experience and how I spend my time outside the firm.
As a tax professor at Georgetown University Law Center and an approved arbitrator for FINRA, Dan has an affinity for sharing his knowledge with others. He is a frequent speaker on webinars and at external tax conferences, and he writes for tax publications like the Daily Tax Report and Tax Notes Today. Previously, Dan served as the Chair of the Banking & Savings Institutions Tax Committee of the American Bar Association’s Tax Section.
Outside of the office, Dan’s hobbies include pickleball, tennis, swimming, and most importantly, spending time with family.
President Donald Trump signed the Doug LaMalfa Federal Disaster Tax Relief Certainty Act into law on September 11, 2026. The legislation extends and formalizes federal tax relief for individuals who sustain losses from major disasters or receive compensation related to certain wildfires. The law addresses a recurring practical problem. Although taxpayers may suffer substantial uninsured…
As the year draws to a close, many business owners focus on budgets, forecasts and operational priorities. Tax planning often becomes an afterthought. That can be a costly mistake. The most effective year-end tax planning for businesses rarely involves aggressive strategies or last-minute transactions. Instead, it requires a disciplined review of income, deductions, investments and…
Few partnership tax controversies have generated as much attention in recent years as the fight over the scope of the self-employment tax exception for limited partners under §1402(a)(13). The Fifth Circuit’s decision in Sirius Solutions (now K. Alain) marked a notable development in August 2026, and the latest chapter arrived on September 17 with the…
What Is a Basket Swap? For years, many fund managers and tax advisers viewed the 70/30 basket swap, a derivative that references a basket of securities rather than a single position, as a reliable way to manage investment risk while preserving the intended tax treatment of the underlying positions. The premise was straightforward: if a…
For years, businesses and tax advisors have searched for a clear answer to a deceptively simple question: When is a limited partner truly a “limited partner” for self-employment tax purposes? Earlier this year, the Fifth Circuit appeared to provide that answer, tying the analysis largely to a partner’s legal status and liability protection. Many taxpayers…
Prediction-market event contracts raise unresolved federal income tax questions because they combine features of wagers and financial instruments. A typical contract may allow a participant to buy a “yes” or “no” position on whether a specified event will occur—such as the outcome of a sports contest, election, weather event or other real-world contingency. Economically, these…
For years, S corporations have been the entity of choice for many closely held businesses. The structure offers pass-through taxation, generally avoids a second layer of tax and provides operational flexibility. But as founders of S corporations begin planning for a future sale, many discover one of the most powerful tax incentives available to business…
For decades, some tax advisors viewed First-Time Abate (FTA) relief as a one-time administrative benefit — valuable enough that some taxpayers intentionally chose not to use it for relatively small penalties in order to preserve it for a more significant issue later. That strategy may soon disappear. In a significant administrative shift, the IRS announced…