About

Alexei Rivas Castelos, EA
Co-Founder
U.S. Tax Specialist for Expats, Inpats, and Global Mobility Programs
π§ rivascastelos
πͺͺ Enrolled Agent
π B.Sc. Economics & Business Administration
I’m the Co-Founder of CLAN Tax, a U.S. tax preparation service specializing in Americans abroad, foreign nationals in the U.S., and cross-border tax compliance. With over 15 years of experience in U.S. tax, I’ve prepared returns for clients from 100+ countries, managed and consulted on complex global mobility tax programs across multiple industries.
Credentials
Specializations
Professional Experience
Before founding CLAN Tax in 2023, I spent eight years at EY (2011β2019), where I served as U.S. Tax Assistant Manager and Location Leader for U.S. Tax Quality & Risk Management, overseeing over 200 professionals in the U.S. Tax / People Advisory Services practice in Argentina.
Working from Argentina, I supported over ten U.S. EY offices (Mainly Houston, Rochester, Denver, Indianapolis, Atlanta, Dallas, Salt Lake City, Iselin, NY and LA) serving clients across diverse industries including
Working across ten U.S. EY offices gave me exposure to diverse industries and thousands of globally mobile employees, from executives on multi-year assignments to field staff on short-term rotations. Whether you’re a business traveler dealing with state allocations, an expat navigating FEIE for the first time, or an inpat filing a dual-status return, I’ve handled it.
I didn’t just prepare and review tax returns, I signed them. I led consultations on FBAR, FATCA, PFIC, and treaty positions. I managed tax equalization programs and global compensation calculations for internationally mobile employees. I trained teams across six countries on tax software and coached professionals from entry-level to senior ranks. And when the IRS came calling, I was the one to pick up the phone, research and respond to notices on behalf of clients.
From 2019 to 2023, I worked as an independent U.S. Tax Consultant. This is where I learned another critical part of the profession: working with self-employed individuals, business owners, founders, and digital nomads. The tax landscape for entrepreneurs is completely different from corporate employment-Schedule C filings, self-employment tax, estimated quarterly payments, and the unique challenges of location-independent professionals.
This experience, combined with my corporate mobility background, connected all the dots. I now understand U.S. tax compliance from both sides: the corporate sponsored inpat/expat on assignment and the entrepreneur building a business from Kuala Lumpur, Lisbon, Budapest, Oaxaca or Bogota.
Education
Bachelor of Science β Economics and Business Administration
Beyond Tax
When I’m not preparing tax returns, you’ll find me watching volleyball (my favorite sport), baseball or football, or listening to music; anything from rumba to rock. Variety works in life as well as tax planning.
Why CLAN Tax
At CLAN Tax, I’m committed to providing transparent, year-round tax support for individuals with U.S. tax obligations anywhere in the world. My approach combines deep technical expertise with clear communication. I don’t assume you speak tax fluently, and I don’t expect you to.
Whether you’re an expat filing FBAR for the first time, an inpat navigating dual-status returns, a digital nomad figuring out an exclusion vs a credit, or a company managing global mobility tax programs, I bring the experience and insight to simplify U.S. tax compliance.
I took what actually works, the good parts of big accounting, real tax experience, compliance, and strategy.
Cut out the noise. The endless layers of people who just donβt care.
Put service back where it belongs. Real service. The kind that means something.
That’s what CLAN Tax is built on.


