Global tax strategies positioning your business for your next move

Rook International CPAs is a family-owned, international tax firm providing services to business owners in and outside the US.

Discover Our Services

We’re personally based in Madrid, but our business is in the US. Want to be sure your business taxes are optimized for your location? Let’s connect!

We ensure your business is designed to weather all elements.

Moving to Europe with a business? Bienvenidos from Spain! We’ve been there, done that. Now, we’re committed to designing custom tax strategies that ensure your business is ready for its European chapter.

6 Continents

We specialize in serving clients currently in or moving to Europe, but we’ve worked with clients almost everywhere.

7 Years

Working in expat taxes, helping business owners insulate their US tax returns from the IRS.

2 Languages

The entire team at Rook CPAs grew up in two languages, and we know the American Dream can be accented. We welcome US business owners from all backgrounds.

Move Abroad from the US with Your Business

We know it’s possible (and can feel daunting) because we’ve personally done it! Rook International CPAs and Advisors is a US-owned firm specializing in tax planning services for established and growing business owners. We believe that, with the right plan in place, moving abroad with a business is a decision that leads to increased opportunities and a better work-life balance. Let us handle your tax affairs so you can enjoy the Dolce Vita, wherever you are.

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Set Up (Or Reorganize) Your Business in the US with a Trusted Tax Partner

The US market is a potentially lucrative one to tap, but you want to make sure you’re set up for success. Our inbound business advisory service emphasizes forward-thinking planning and strategic execution so that you can focus on growing your business without fear that you’ve made a costly miscalculation, incorrectly filed a form, or missed a filing deadline.

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Testimonials

See what our clients have to say about us.

"
I own and operate 6 companies in the Netherlands as well as a property management company in the USA and handle 100% of my American tax responsibilities together with Rook International. They are extraordinarily knowledgeable and showcase their understanding in every call we have.

Josh B.

Netherlands

"
Nicolas Castillo's knowledge and guidance of the US tax preparation process is excellent. He took the time to explain everything clearly, answer questions, and help me identify deductions and credits I wasn't aware of. His proactive approach and attention to detail resulted in substantial savings. I highly recommend his services to anyone seeking a reliable and trustworthy US CPA.

Alexander C.

Spain

"
As the founder of a company that supports Americans relocating to Portugal, Nicolas is an invaluable partner for Americans living abroad as business owners or freelancers. What sets Nicolas apart is his ability to collaborate seamlessly with my Portuguese accountant, ensuring tax accuracy in both countries. Beyond my own business, he’s also helped countless members of our network navigate the complexities of US taxes while living abroad.

Amy K.

Portugal

"
As an American citizen living in Spain, I wasn’t sure how to navigate the complexities of international taxes, working for a US company, and buying a property in Spain. Rook CPAs made all of that look easy! Nicolas was very diligent and responsive, and he worked on a tight deadline to make sure I filed on time. Totally recommended!

Andrea Q.

Spain

Plan Your Every Move with Purpose

We’re hanging up the traditional CPA-client relationship model and creating something new and bold for global business owners – and we’d love you to consider this your official invitation to be a part of it.

Meet the Team

What's Better Than a Virtual Meeting? An In-Person One

A handshake that you hope was firm enough, but not too firm. The initial feeling of awkwardness changing to a growing sense of confidence that you're actually getting to know someone. Talking about why you built your business. Learning how to think beyond compliance and lean into tax planning and strategy.

You Seem Like Someone Who Likes Learning

Visit our library of educational resources, featuring our latest blog articles, media appearances, and upcoming in-person events.

Enter The Library

By Nicolás Castillo | 30 Jan, 2026 | IRS general forms, US business

What Is Signature Authority on a Bank Account for FBAR?

When people hear “FBAR,” they usually think about owning foreign bank accounts. But ownership (also referred to as having a “Financial Interest” in a foreign bank) of a foreign bank account is only part of the picture. The FBAR rules also apply to people who don’t own the money at all, but still have the power to control what happens to it. That’s where signature authority comes in.

By Nicolás Castillo | 27 Jan, 2026 | IRS business tax forms, IRS general forms

What Is a PFIC? A Guide to Rules, Reporting for US Expats

PFIC is one of those terms that almost guarantees confusion the moment it enters the conversation. It stands for "Passive Foreign Investment Company," but that label alone explains very little. In practice, PFIC rules are one of the most frustrating parts of the U.S. tax system. They can affect Americans living abroad, which is the more common way the topic surfaces. However, they can also affect Americans in the US who previously worked abroad or inherit investments.

By Nicolás Castillo | 5 Dec, 2025 | Portugal

NHR 2.0: The IFICI Opportunity for US Business Owners in Portugal

When Portugal’s beloved Non-Habitual Resident (NHR) program closed to new applicants in 2024, many expats and ...

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