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DELTA AUDIT GMBH is a supra-regionally active auditing and tax consulting company founded in 2006 and based in Mainz.

Our clients include medium-sized industrial and service companies, commercial enterprises, public sector institutions, associations, freelancers and private individuals. The clientele ranges from family groups to employees and consortia of companies. It forms a representative section over all occupational groups and industries. We attach great importance to lasting business relationships. The guarantee for this is the mutual trustful cooperation.

The company has successfully participated in the quality control system of the Chamber of Auditors. The certificate of participation is dated November 07, 2018.



Dipl. Kaufmann

Christian Müller

Auditor, Tax consultant
  • Business studies at the University of Trier, graduation as Dipl. Kaufmann 1994

  • Appointment as tax consultant 1999

  • Appointment as auditor 2004

  • Foundation of DELTA AUDIT GmbH 2006

  • Languages: German, English

Mr. Christian Müller, began his professional career in 1995 at a medium-sized auditing company in Koblenz, where he focused on auditing and advising municipal public enterprises and municipal corporations for more than seven years. He then worked for a further three years in a law firm in Wiesbaden, where he mainly advised medium-sized clients. Since 2006 he has been managing director and shareholder of DELTA AUDIT GmbH.




Dipl. Betriebswirtin

Veronique Steiniger

Tax and Audit Assistant

Studies at the TH Aschaffenburg University of applied sciences

worked for a Big 4 company from 2007 to 2013

since 2014 at DELTA AUDIT GmbH

Languages: German, English


Bachelor of Science

Mariam Abou Taam

Audit Assistant 

Studies at the Distance University of Hagen

since 2019 at DELTA AUDIT GmbH

Languages: German, English, Arabic


Master of Science

Purya Azhang

Audit Assistant

Studies at the University of Tehran

Many years of experience as a broker on the Tehran Stock Exchange

since 2019 at DELTA AUDIT GmbH

Languages: German, Persian, Kurdish


Bachelor of Science

Ömer Kilic

Audit Assistant

Studies at the Technical University of Cologne

since 2020 at DELTA AUDIT GmbH

Languages: German, English, Turkish


Master of Science

Dhurata Sino


Studium an der Universität Tirana

seit 2024 bei der DELTA AUDIT GmbH

Sprachen: Deutsch, Albanisch, Englisch

  • Our goal is an optimal and individual support of our clients on the basis of their needs and ideas.

  • We do not only want to relieve our clients of burdensome duties, but also to provide them with asset advantages through tax and business management consulting

  • We want to exceed the expectations of our clients


Our core activity is auditing and all related activities. In addition, we are active in tax consulting and advise on tax law issues as well as, in cooperation, on legal issues. We aim to provide our clients with comprehensive and solution-oriented advice based on our expertise and the resources available to us. The client and his individual challenges are our focus. We are 100% committed to our clients and treat their personal matters with utmost discretion. We work prudently, conscientiously, reliably and efficiently. We always offer the best processing of the information given to us using the latest technology and the best advice.

What makes our firm special and what we are proud of is our long-term trusting relationships with our clients. We are a TEAM and everyone contributes to our common success. We also live this team spirit with our clients. Every day again and every day with the same fun! A cheerful working atmosphere based on partnership is important to us, as well as cooperation based on respect and openness.

We are committed to a strict quality assurance concept and offer our employees regular training and continuing education to ensure the highest quality for our clients.


Tax consultancy


In principle, we carry out our assignments as tax consultants in accordance with the "General Terms and Conditions of Assignment for Auditors and Auditing Firms". The calculation of our fee is generally based on the Tax Advisor Remuneration Ordinance (Steuerberatervergütungsverordnung) and is thus based on legally prescribed subject matter values. However, it is also possible to freely negotiate a time- and value-based fee.


The fee for audits is freely negotiated without exception, as there is no statutory regulation.



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