In the tax market, experience is currency. And few can claim a richer résumé than MD Sullivan, a former IRS Revenue Officer whose career has evolved from frontline asset seizures to national mentorship. But Sullivan didn’t just shift roles; he transformed the entire picture of tax resolution by mentoring thousands of professionals and creating a unified platform for collaboration: The Tax Mob.
His influence has rippled through courtrooms, classrooms, and online communities, earning him recognition as one of the most trusted and dynamic voices in IRS tax resolution. What makes Sullivan’s mentorship so unique is that it’s rooted in both theoretical knowledge and practical, real-world enforcement experience.
Before Sullivan ever taught a seminar or founded an online group, he was a field agent operating in one of the most intense environments imaginable: South Florida during the 1980s drug war. Working on the IRS’s Narcotics Trafficking Task Force, he specialized in high-stakes seizures, including boats, vaults, homes, vehicles, and businesses, all tied to unreported income and money laundering.
That hands-on, high-pressure experience provided Sullivan with a comprehensive understanding of IRS procedures, lien enforcement, asset forfeiture, and collection statutes. But more importantly, it gave him a roadmap for teaching others, because he didn’t just know what to do, he knew why it was done and how to navigate the system when it didn’t go as planned.
When Sullivan transitioned into private practice after nearly a decade with the IRS, his reputation for knowledge and professionalism followed. Recognizing a loophole in the training structure, he began offering instruction to young tax professionals, many of whom were overwhelmed by the complexity of IRS systems like the Offer in Compromise (OIC), Trust Fund Recovery Penalty (TFRP), and Collection Due Process (CDP) hearings.
He was later certified by the Florida Department of Professional Regulation to train CPAs and tax attorneys in IRS representation. His approach wasn’t dry or formulaic. Instead, it was practical, scenario-based, and full of insight into the IRS’s internal decision-making process.
In addition to in-person training, Sullivan served as an on-the-job instructor during his IRS tenure, coaching new Revenue Officers and helping them grasp the technical and emotional nuances of enforcement. This dual background (teaching inside the system and mentoring outside of it) made Sullivan an invaluable asset to professionals looking to fast-track their expertise.
Sullivan’s largest and most lasting contribution to tax education, however, came in the form of a Facebook group. Started with a few dozen colleagues, the Tax Mob quickly exploded into a vibrant online hub with over 5,300 members, including IRS alumni, tax attorneys, enrolled agents, and CPAs from across the United States. What sets it apart from other forums is its openness, high-level dialogue, and cross-disciplinary collaboration.
Inside the group, members share strategies on IRS notices, discuss policy changes, troubleshoot complex OIC scenarios, and swap war stories. Sullivan moderates with humor, clarity, and authenticity, offering his own experiences freely and encouraging a culture of mutual support.
The group has helped elevate the field by democratizing insider knowledge and creating a space where no question is too basic, and no insight too advanced. It has become especially vital in a post-pandemic world, where IRS backlogs, automation, and AI-generated notices have complicated resolution pathways.
Out of this digital hub came something even more powerful: an annual gathering known as the Tax Mob Convention. Held in cities like Las Vegas, Nashville, Denver, and Puerto Rico, these events blend Continuing Professional Education (CPE) with relationship-building and one-on-one mentorship. Sessions include live case clinics, roleplay audits, policy deep-dives, and panel discussions with former IRS agents and attorneys.
For many, it’s the only place where seasoned professionals and fresh-faced practitioners can meet, learn, and share the same table. He also uses these gatherings to spotlight rising stars in the profession, encourage collaboration across disciplines, and continue his mission of mentoring at scale.
Sullivan’s YouTube channel, ‘Help from a Former IRS Agent,’ is another branch of his mentorship legacy. With over 1.7 million views, it covers topics like penalty abatement, audit preparation, IRS hardship rules, and navigating levies and garnishments.
What makes the channel so engaging is Sullivan’s ability to break down complex topics in plain English, using real-world examples from his vast case history. His presence on national media, FOX Business, NewsNation, ABC, and others has further expanded his reach and credibility.
Whether he’s training a young CPA in Fort Lauderdale, organizing a panel in Puerto Rico, or sharing laughs in a Facebook thread, Sullivan continues to serve as the field’s most generous mentor. For Sullivan, mentoring isn’t a side project. It’s a mission, and the tax resolution world is better for it.
