Nicolás Castillo, CPA

Nicolás Castillo is a U.S. Certified Public Accountant (CPA) and the founder of Rook International CPAs & Advisors, a cross-border tax and advisory firm serving U.S. business owners and globally mobile professionals living in or moving abroad.

Born and raised in Miami in a Cuban-American family, Nicolás grew up navigating multiple cultures, languages, and financial systems—an experience that now shapes his work with internationally minded clients. He specializes in U.S. tax compliance and planning for Americans with foreign businesses, cross-border income, and complex international lives, with particular depth in Europe.

Nicolás is known for helping clients make high-stakes relocation decisions with clarity and confidence, especially when business ownership is involved. His work goes beyond annual tax filings to focus on structure, timing, and long-term sustainability—ensuring that clients don’t accidentally create double taxation, compliance risk, or costly mistakes when moving abroad.

In addition to standard business tax planning and strategy work for U.S. expats, we've developed two core advisory offerings to meet global entrepreneurs, digital nomads, and small business owners where they're at.

Moving Abroad Business Advisory Package (MABAP)

The Moving Abroad Business Advisory Package (MABAP) is a pre-move planning engagement for U.S. business owners preparing to relocate abroad. It’s built on a simple reality: the most important tax and structural decisions happen before you move.

MABAP includes a joint advisory call with Rook and a vetted local tax partner in one of our core jurisdictions (Spain, Portugal, France, or Italy), ensuring your U.S. and local tax strategies are aligned from day one. Together, we evaluate your business structure, income flows, and residency timing to prevent double taxation and compliance issues.

Following the session, you receive a clear, written roadmap outlining next steps and priorities—so you can execute your move with confidence and avoid costly mistakes after residency begins.

Learn more about the MABAP here.

Moving Abroad Tax Advisory (MATA)

The Moving Abroad Tax Advisory (MATA) is a pre-move planning engagement for U.S. individuals and families preparing to relocate abroad. It’s designed around the same principle as MABAP: the most important tax decisions happen before you move.

MATA includes a joint advisory call with Rook and a vetted local tax partner in one of our core jurisdictions (Spain, Portugal, France, or Italy), ensuring U.S. and local tax rules are aligned from the start. We help clients understand how investments, retirement accounts, rental property, and future real estate plans will be treated after the move.

You’ll receive a clear, written roadmap outlining next steps—so you can relocate with confidence, avoid surprises, and make informed decisions about your financial life abroad.

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.