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Stefan Sinne is a banker and studied Business Administration at the University of Cologne from 1991 to 1996. After graduating in 1996, he started his professional career at the former Warth & Klein GmbH. In 2000 he became Tax Advisor and in 2002, German Public Auditor. Subsequently he was appointed Associate Partner in 2012 and Partner in 2017. Since 1 January 2019, Stefan Sinne has been Equity Partner at Grant Thornton AG.

Stefan Sinne is responsible for engagements with national and international companies of various sizes and legal forms, including listed entities. The focus of his activities is on audits of annual financial statements, and audit and advisory of energy intensive companies, especially within the special compensation scheme of the Renewable Energy Law [Erneuerbare Energien Gesetz - EEG]. In addition, he has long-term experience in the preparation of expert opinions in in-court and out-of-court litigation.

Stefan Sinne is registered as Quality Control Auditor. Stefan Sinne is a member of the Energy & Natural Resources Industry Group, where he is responsible for special matters related to limitation of apportionment under the Renewable Energy Act [EEG]- and other energy-related aids.

In the meeting the advisory council of the Chamber of German Public Auditors [Wirtschaftsprüferkammer] on 4 December 2019, Stefan Sinne, German Public Auditor/Tax Advisor, was unanimously elected member of the Commission for Quality Assurance [Kommission für Qualitätskontrolle - KfQK] with effect from 17 January 2020.

Fields of expertise

  • Audits of financial statements and consolidated financial statements for medium-sized enterprises
  • Quality controls according to section 57a et seq. German Auditors' Code [Wirtschaftsprüferordnung - WPO] (Peer Review)
  • Audits according to special legal regulations (e.g. EEG [Renewable Energy Law], KWKG [Cogeneration Protection Law], KAV [Concession Charges Regulation])
  • Expert opinions
  • Advice on corporate transactions
  • Forensic & Investigations


  • Member of the quality control commission of the Chamber of German Public Auditors
  • Member of the "Digital long-form audit report and Auditor's Report" of the Institute of Public Auditors in Germany [Institut der Wirtschaftsprüfer e.V. (IDW)]
  • Chamber of German Public Auditors [Wirtschaftsprüferkammer]
  • Düsseldorf Chamber of Tax Consultants [Steuerberaterkammer Düsseldorf]
  • Diplom-Kaufmann [Graduate in Business Administration]
  • Tax Advisor
  • German Public Auditor
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