Nicolás Castillo, CPA

U.S. Cross-Border CPA & Expat Business Tax Advisor for Americans Moving to Europe

Born and raised in Miami in a Cuban-American family, I grew up navigating multiple cultures, languages, and financial systems. That experience now shapes how I work with internationally minded clients as a U.S. Certified Public Accountant and founder of Rook International CPAs & Advisors.

I specialize in U.S. tax compliance and planning for Americans with foreign businesses, cross-border income, and complex international lives, with particular depth in Europe. My work goes well beyond annual filings. The clients I serve are making high-stakes relocation decisions that carry real structural and timing implications: business entity choices, income flow analysis, residency planning, and long-term sustainability across two tax systems. Getting those decisions wrong  (or making them too late) is where double taxation, compliance risk, and costly mistakes are born.

Listen to Nicolás' episode on Passport to Wealth™ here.

About Rook International CPAs & Advisors

Rook International is a cross-border tax and advisory firm serving U.S. business owners and globally mobile professionals living in or moving abroad. In addition to ongoing U.S. expat tax planning and strategy, we've developed two structured pre-move advisory engagements built around a straightforward reality: the most consequential tax decisions happen before you relocate.

Moving Abroad Business Advisory Package (MABAP)

MABAP is a pre-move planning engagement for U.S. business owners preparing to relocate abroad. It includes a joint advisory call with Rook and a vetted local tax partner in one of our core jurisdictions ensuring U.S. and local tax strategies are aligned from day one. We evaluate business structure, income flows, and residency timing, then deliver a clear written roadmap so clients can execute their move with confidence.

Learn more about the MABAP here.

Moving Abroad Tax Advisory (MATA)

MATA is the individual and family equivalent; a pre-move planning engagement covering how investments, retirement accounts, rental property, and future real estate plans will be treated after relocation. Like MABAP, it includes a joint call with a vetted local tax partner and concludes with a written roadmap outlining next steps and priorities.

Please note that the above programs are currently only available for Spain, France, Italy, and Portugal. 

We remain available to support U.S. business owners on the U.S. tax planning and strategy side of things anywhere in the world. Visit our website or book directly with a Rook team member to get clear answers to learn about how we can support you.