.png){kind=spacer}
Who we are
KSI Attorneys-at-law LLC is a boutique tax firm founded by Kevin Sirman, a Franco-Swiss attorney-at-law with over 9 years of experience in international tax law, registered at the Geneva and Paris Bar Associations.
Prior to founding the Firm, he began his career at the tax department of a French leading international energy group, before joining two of the world's foremost tax advisory firms — first in France, then in Switzerland. This experience at the heart of two of Europe's major financial centres gave him a thorough command of international tax in both the French and Swiss contexts. He then joined a Geneva-based law firm, where he refined his practice serving international private clients, before launching his own firm.
Our practice is built around a simple conviction: complex international situations deserve senior-level attention, not commoditised advice. Every client works directly with experienced counsel.
We operate from Geneva, Paris, and São Paulo, and advise clients across Europe, the Americas, and beyond. Our working languages are English, French, and Portuguese, with conversational Russian.
9+ years of experience in international tax law
4 languages — English, French, Portuguese, Russian
3 offices — Geneva, Paris, São Paulo
Specialized expertise where it matters most
US tax law
Navigating US tax obligations across borders
US citizens and green card holders are taxed on their worldwide income, regardless of where they live. For Americans residing in Switzerland, this creates a layer of complexity that most advisors are ill-equipped to handle.
We advise US-connected clients on the full spectrum of their cross-border obligations: FBAR and FATCA reporting, treatment of foreign accounts and investment structures, as well as the coordination of US and local tax liabilities under applicable tax treaties.
Whether you are relocating, restructuring, or simply seeking to bring your situation into compliance, we provide practical, legally certain solutions — without unnecessary exposure.
Brazilian tax law
Deep expertise in Swiss-Brazilian tax matters
Brazil's tax system is among the most complex in the world, and its interaction with Swiss and French rules creates situations that require genuine specialist knowledge — not generalist advice.
We assist clients with ties to Brazil in navigating the Switzerland-Brazil tax treaty, the social security convention, and the specific rules governing the taxation of Brazilian-sourced income and assets held abroad.
From structuring holding arrangements to advising on succession and wealth planning across both jurisdictions, we deliver tailored solutions that reflect the legal realities of both systems.
Protecting your interests when it matters most
Tax disputes with Swiss or French authorities can carry significant financial and reputational consequences. Whether you are facing an unexpected tax assessment, a challenge to your residency status, or an audit targeting your international structure, you need an attorney who combines technical depth with real litigation experience.
At KSI Attorneys-at-law LLC, we represent high-net-worth individuals and families at every stage of the dispute — from the first administrative exchange to proceedings before the competent courts. Our approach is strategic: we assess your exposure early, engage with authorities from a position of strength, and leverage applicable tax treaties to contain your risk.
We notable assist you with the following matters:
— Challenges to tax residency determinations (Swiss and French authorities)
— Disputes over the taxation of foreign income, trusts, and international structures
— Defense in wealth tax and succession tax assessments
— Treaty-based claims and mutual agreement procedures (MAP)
— Voluntary disclosure and regularization of undeclared assets
Litigation is never our first recommendation — but when it becomes necessary, we are fully equipped to defend you.
What we do
Tax Litigation
We represent clients in complex disputes before Swiss and French tax authorities, from administrative challenges to court proceedings. We defend against assessments, contest residency determinations, and leverage treaty protections to minimize exposure.
Tax Advising
We advise on international tax planning, cross-border structuring, and private wealth organization — including lump-sum taxation negotiations, holding structures, and the coordination of tax exposure across multiple jurisdictions.
Corporate Law
We assist entrepreneurs and investors with company formation and governance, from Swiss SA/AG structures to international holding arrangements, ensuring seamless cross-border establishment and long-term compliance.
Immigration law
We advise high-net-worth individuals and entrepreneurs on Swiss residence permits, work authorizations, and lump-sum taxation regimes — streamlining the path to tax-efficient relocation for investors and professionals.
Insights
Articles published for the Swiss-Brazilian Chamber of Commerce
Saída definitiva da Suíça: Solicite o reembolso das suas contribuições salariais!
Relocação para a Suíça: O Caminho para Estabilidade, Oportunidade e Qualidade de Vida
Frequently Asked Questions
Death and taxes are certain. But we will handle the second ones.
Contact
Whether you have a specific question or simply want to explore whether we can help, we welcome an initial conversation. All exchanges are strictly confidential.
Geneva - Switzerland
35, rue des Bains
1205 Geneva
Paris - France
87, boulevard Malesherbes
75008 Paris
São Paulo - Brazil
205, Rua Olimpíadas, Vila Olímpia
São Paulo - SP, 04551-000
+41 78 626 58 78
+33 642 53 60 37
Affiliations
