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Press Release

Two new partners at Grant Thornton: Isabel Derison & Emmanuel Mariage

Isabel Derison and Emmanuel Mariage further consolidate Grant Thornton’s position as a full-service business consulting firm in Belgium

Grant Thornton Belgium, the consulting firm with expertise in auditing, accountancy, tax & legal affairs and corporate advisory services, continues its ongoing growth with the appointment of two new partners: Emmanuel Mariage and Isabel Derison. This consolidation contributes to the further broadening of Grant Thornton’s services and underpins the sustained increase in regional expertise. Their appointment brings the total number of partners within the organisation to 24.


Isabel Derison becomes Business Risk Services Partner

Isabel Derison (40) will be taking up her role as Business Risk Services Partner, having already gained broad experience as an auditor during her career thus far. She began as an external auditor at KPMG and then took up a post as internal auditor at SD Worx. Over the last five years she has set up the internal audit function at ZNA, the largest hospital network in Belgium. She is also president of the Belgian Institute of Internal Auditors (’IIA’), the professional association of internal auditors in Belgium – a position she took up last year.

Her experience and the fresh view she brings to auditing, governance and risk management form the basis to provide businesses with tailor-made advice. In the future the focus is to be placed chiefly on those developments and trends that companies are concerned about.

“I notice that companies are faced with numerous challenges and questions regarding how best to approach and guarantee compliance in areas such as sustainability, also referred to by the acronym ESG (Environment - Social - Governance), digitisation or implementation of the EU whistleblower protection*. What we want to do above all at Business Risk Services is to turn risks and challenges into certainties and opportunities”, Isabel Derison adds.

Emmanuel Mariage becomes Direct Tax Partner

Emmanuel Mariage (46) becomes Direct Tax Partner. He also started his career at KPMG, but as a tax adviser. He continued his career at De Witte-Viselé Associates (DWVA), which joined Grant Thornton’s network in 2017 and from where his career growth internally led to him taking on the position of partner.

“The affiliation of DWVA was in line with Grant Thornton’s strategy of further developing their advisory services in the Walloon Region”, says Emmanuel Mariage. “Today we maintain the same objective. In this region we offer high-level accountancy and tax services.”

“What’s more, over the years we have developed the necessary expertise in optimising and reducing the advance levy on income derived from real estate and local taxes for companies established in the Walloon Region. My ambition is to extend our services in Wallonia still further, mainly in the provinces of Brabant wallon and Namur.”

Both appointments are in line with Grant Thornton’s growth strategy

“The appointment of Isabel and Emmanuel is part and parcel of Grant Thornton’s growth strategy”, says Ria Verheyen, Managing Partner of Grant Thornton Belgium. “Our clients face numerous challenges. We invest very specifically in staff with a view to further developing and extending our services, both within the various business areas and geographically.”

“With their expertise, Emmanuel and Isabel provide us with the necessary extra knowledge  and experience. Their appointment is one of the factors that will enable us to further add to and expand our range of services.”



* The EU Whistleblow directive aims to provide common minimum standards of protection across the EU to whistleblowers who raise breaches of EU law within a work-related context.

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