
Co-Founder & COO · Your Tax Base
Brett Sullivan
Runs operations and compliance, and turns bureaucratic chaos into one clean checklist.
Brett studied accounting and finance and grew up working in and around his family’s accounting firms, where tax season is the family business. What stuck with him was less the numbers than the mess: the tangle of forms, agencies, and deadlines that leaves most people stuck. He is at his best turning that chaos into a clean, repeatable checklist.
A couple of years living in Europe put him in the middle of the expat community and its recurring problems: filing US taxes from abroad, keeping US bank accounts alive, and mail that never stops arriving. He met Justin at Money20/20 Europe, shared the advice that was obvious from inside an accounting family, and together they turned Justin’s one-day domicile playbook into Your Tax Base.
As Co-Founder and COO, Brett runs the operations and compliance behind the service: building the process, keeping every customer’s documentation accurate and audit-ready, and making sure the whole move stays simple and human, with CPAs on the ready when a situation calls for one.
We met at Money20/20 Europe: one of us living the expat problem from the inside, the other from a family of accountants and CPAs. The advice traded that week became a one-day Florida domicile playbook, and the playbook became Your Tax Base.
Latest articles by Brett
Which State Should Hold Your US Driver License When You Live Abroad [2026 Comparison]
Expat Tax Planning · 13 min read · Aug 20, 2026
Notarizing US Documents From Abroad: Why Identity Verification Fails and What to Do Instead
Expat Taxes · 17 min read · Jul 21, 2026
Articles reviewed by Brett
Can I Use My Parents' US Address While Living Abroad?
Expat Taxes · 12 min read · Sep 25, 2026
Can You Keep Florida Residency After Selling Your House? The 2027 Guide for Full-Time Travelers
Florida Domicile · 21 min read · Sep 7, 2026
California's Two New Taxes for 2027: What SB 122 and SB 125 Actually Cost You (and the One Tax Cut Sacramento Can't Block)
Tax Migration · 19 min read · Jul 9, 2026
How to Open a US Bank Account From Abroad in 2026
Expat Tax Planning · 33 min read · Jun 29, 2026
Expat & Migration Statistics 2026: How Many Americans Live Abroad, Where U.S. Income Moves, and What Changes in 2027
Expat Tax Planning · 27 min read · Jun 6, 2026
Changing State Residency While Living Abroad
Expat Tax Planning · 3 min read · Jun 3, 2026
The Florida "Six Months and a Day" Residency Myth: What Actually Establishes Domicile in 2026
Florida Domicile · 20 min read · May 10, 2026
Florida Domicile Before Moving Abroad: A Pre-Departure Handoff Plan
Expat Tax Planning · 4 min read · May 7, 2026