Tijmen is a partner at Rutgers & Posch and has been with the firm since it was founded. He specialises in employment law and is a certified pension lawyer (CPL). Besides his work in pension law, Tijmen also focuses on remuneration policies and remuneration legislation such as the Dutch Remuneration Policy (Financial Enterprises) Act (Wet Beloningsbeleid Financiële Ondernemingen) and the Dutch Standards for Remuneration Act (Wet Normering Topinkomens). He has also helped numerous Dutch and foreign companies with the employment-law aspects of reorganisations, mergers and acquisitions and co-determination processes.
Before Rutgers & Posch was founded in 2013, Tijmen worked for various other firms including Kennedy Van der Laan and DLA Piper. Tijmen is a member of the editorial staff of company lawyer journal Bedrijfsjuridische Berichten, and a board member of the Amsterdam Employment Lawyers Association. He is also a member of the Assembly of Delegates of the Amsterdam Bar.