French & Swiss taxation · Advisory and litigation
Lawyer in Geneva
A law firm dedicated to tax and business law. We advise and defend companies, executives and families, in Switzerland and in France.
Two offices, Annecy and Geneva, a single point of contact.
The firm
A law firm dedicated to tax law, based in Geneva.
COTAX acts for companies and groups, their executives and shareholders, as well as for individuals and families whose wealth has an international dimension.
Our practice covers the full cycle: audit, structuring, reporting obligations and, where necessary, tax audits and litigation. Every situation is read simultaneously under Swiss and French law.
Geneva taxation combines three levels of tax, an administrative practice specific to the AFC and short procedural deadlines. Our work is to secure upstream what can be secured, and to defend downstream what must be defended.
Discover our tax practice in detail on our page tax lawyer in Geneva.
- Absolute confidentiality, in advisory work as in litigation.
- Responsiveness, a single point of contact on both sides of the border.
- Availability, from the initial review to the defence before the tax courts.

Founding partner
Me Gilles Colin, partner
Gilles Colin, partner and member of the bar, has practised tax law, corporate and contract law for twenty years, in advisory work as in litigation. He personally handles every case, from the first meeting to the final decision. The firm works in French, English, Italian and Spanish.
A human-sized firm, with the standards of a large practice.
2
Offices
Annecy and Geneva, a single point of contact on both sides of the border.
2
Legal systems
Every situation is read simultaneously under Swiss and French law.
4
Working languages
French, English, Italian and Spanish, for an international clientele.
20
Years of experience
In tax law, corporate and contract law, advisory and litigation.
Our expertise
Two client bases, one technical standard.
Our services
Explore all our practice areas.
Our approach
From diagnosis to defence, a method in three stages.
Diagnosis
A full tax review of your situation, under French as well as Swiss law, before any recommendation. We identify open risks, running deadlines and the tax optimisation genuinely available.
Structuring
Documented and secure structures: technical memos, sources and case law cited, risks identified.

Defence
Handling audits and litigation, from the initial objection up to the administrative and federal courts.
Our commitments
A practice built on principles, proven by experience.
Three commitments define our relationship with every client: confidentiality, responsiveness and availability. The rest is a matter of method.
Confidentiality
Legal professional privilege protects every exchange, from the first meeting to litigation.
Responsiveness
Short tax deadlines require fast answers. We organise ourselves to meet them.
Availability
A single, reachable point of contact who knows your file from end to end.
Technical rigour
Documented recommendations: technical memos, sources and case law cited, risks identified.
Cross-border reading
Tax treaties, double taxation, administrative assistance: both legal systems, simultaneously.
Independence
Advice free from any commercial interest, focused solely on the security of your situation.

Every case is handled personally, from the first meeting to the final decision.
We receive clients by appointment only, in Geneva. Describe your situation and we will tell you clearly what is at stake and how we can assist you.
Book an appointmentConfidentiality · Responsiveness · Availability
Frequently asked questions
Answers to the most common questions about the firm, how an engagement unfolds and the way we work.
Another question?
Ask a questionCOTAX is dedicated to tax law: taxation of individuals and families, taxation of businesses and executives, VAT and indirect taxes, tax litigation and voluntary disclosures. The firm also advises on corporate and contract law.
Yes. With two offices, in Annecy and Geneva, every situation is analysed simultaneously under French and Swiss law: tax treaties, double taxation, administrative assistance and automatic exchange of information.
We receive clients by appointment only, in Geneva or remotely. The first meeting is used to set out your situation, identify the issues and define the right course of action: audit, structuring or defence.
Fees are presented at the appointment, depending on the nature of the matter. They are set out in a clear agreement before any work begins.
Absolutely. Legal professional privilege covers all our exchanges, from the very first contact, in advisory work as in litigation.
The firm works in French, English, Italian and Spanish, for a Swiss and international clientele.
Insights
Briefing notes and tax news.
A tax question between France and Switzerland?
Set out your situation in a confidential appointment. We answer with precision, under Swiss as well as French law.
Law firm in Geneva · 35, rue des Bains, 1205 Geneva · Monday to Friday
