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Jan van Nass

Jan specialises in complex corporate and commercial disputes. He is well versed in matters relating to commercial contracts, post M&A disputes, joint ventures as well as professional liability and director liability. He represented clients across various sectors including private equity, finance, energy, accountancy and government.
Jan has been in practice as an attorney since 2007. Prior to co-founding Ysquare, Jan worked in the commercial litigation departments of Allen & Overy and BarentsKrans for over 8 years, litigating a variety of contentious matters. Subsequently, Jan gained practical experience by working as in-house counsel at KPMG for several years, managing the company’s professional liability cases. He completed the Grotius postgraduate course on National and International Contract Law as well as a postgraduate course on Financial-Economic Criminal Law at the VU University Amsterdam. Jan is admitted to the Dutch Bar and is a member of the Corporate Litigation Association, the Accounting Law Association and the Procedural Law Association.

Recent work

  • Arbitration for Dutch beer brewer regarding contractual dispute with US logistics supplier.
  • Litigation for the sellers of an education company regarding an earn-out and alleged warranty breaches.
  • Litigation for joint venture partner regarding the application of a contractual share offer arrangement.
  • Various disciplinary and civil proceedings regarding the auditors’ professional liability.
  • Litigation for professional services firm regarding its professional liability.
  • Litigation for a Dutch oil refinery regarding a contractual dispute with a technology supplier. Summary arbitral proceedings for a Dutch energy provider regarding a contractual dispute with a strategic supplier.
  • Litigation for the former CEO of a public company regarding directors’ liability in bankruptcy.
  • Litigation for a foreign central bank regarding its alleged liability in respect of the bankruptcy of a Dutch subsidiary bank.
  • Litigation for a public institution regarding a contractual dispute with a union.


Professional background

  • Since 2019

    Ysquare | Attorney-at-law

  • 2016 – 2019

    KPMG | Attorney-at-law (in-house)

  • 2012 – 2016

    BarentsKrans | Attorney-at-law

  • 2007 – 2012

    Allen & Overy LLP | Attorney


  • 2018

    VU Amsterdam | Postgraduate in Financial-Economic Criminal Law

  • 2014

    Grotius Academy | National and International Contract Law

  • 2007

    Leiden University | LL.M.

  • 2000

    Université Paul Valéry, Montpellier | Diplôme approfondi de langue française

Jan van Nass image


  • Dutch
  • English
  • French
  • German
Jan van Nass image


  • Dutch
  • English
  • French
  • German