Since August 2005, Jos has worked at De Haan Lawyers & Solicitors. Jos is not only a lawyer at the district court of Groningen (1993), but has also been admitted as a German lawyer (Rechtsanwalt) (1997) at the district court of Hamburg. To be admitted, he had to complete postgraduate studies at the Westfälische Wilhelms-Universität in Münster. In 1997, Jos graduated as a lawyer in Stuttgart.
In daily practice, Jos predominantly assists Dutch and German companies in the field of international trade and business law. He specialises in Dutch and German labour law. Jos is partner and co-founder of the German firm Stoffregen & Janssen established in Hamburg | Rechtsanwälte und Lawyer.