Marius Siemen
Attorney at law, Partner
Marius Siemen advises on all aspects of German and international tax law. His work focuses in particular on the global investments of institutional investors and private individuals across all asset classes. He has extensive experience with projects involving German investors in the United States as well as in the Asia‑Pacific region. Another key area of his practice is the representation of clients in tax disputes: from tax audits to administrative appeals and litigation, as well as the support of clients in criminal tax proceedings.
Vita
Education
- Bucerius Law School, Hamburg
- University of St. Gallen, Switzerland
- Higher Regional Court Frankfurt am Main
- Certified Criminal Tax Law Advisor (DAA)
Professional Experience
- Jones Day LLP, Frankfurt am Main, 2020 to 2021
- Noerr PartGmbB, Munich, 2021 to 2025
- Siemen Conrady GmbH, since 2026
Experience
Prior to founding Siemen Conrady, Marius Siemen advised on the following mandates, among others:
Tax Disputes | Tax Litigation | Tax Compliance
- Multiple representation in German tax audits (each involving a dispute volume of over 30 million EUR)
- Advice in connection with criminal tax proceedings/internal investigations into German capital gains tax
- Requests relating to the German conversion clause
M&A | Private Equity | Capital Markets
- Advising DBAG portfolio company SERO on the takeover of EPSA Group
- Advice from Rocket Internet in connection with Elliott's delisting and exit
- Advising EMERAM Capital on the partial sale of its investment in] init [AG
- Advising Hamburg-based online designer fashion marketplace Rebelle.com on its IPO in Stockholm
Real Estate
- Carrying out numerous due diligence reviews and accompanying real estate M&A projects
- Comprehensive experience with typical tax issues of real estate companies in Germany (commercial character, sales tax, etc.)
Private Funds | Limited Partner
- Advice on over 60 LP investments in all asset classes
- Special focus on US funds (including REIT structures), private debt and private equity
- Advising US LPs with investments in German private funds
- Experience with the requirements of German investors under special tax regimes in a private fund context (e.g. life/health insurance and non-profit organizations)
Private Funds | General Partner
- Ongoing advice from GPs on structuring various private funds
- Special experience with Luxembourgish and German fund vehicles
Publications
- “Taxation of crypto assets — changes from the BMF letter dated 6.3.2025” (with Lukas Conrady), BB 2025, 1751-1756;
- “Flat-rate taxation of income from accumulating “black” funds”, Review BFH ruling dated 18.06.2024, VIII R 13/20, RdF 2025, 73;
- “Investments in start-ups — check the return on investment,” DATEV magazine, 27.03.2024;
- Commentary on Sections 30 to 32 InvStG with Dr. Elmar Bindl, in: Jansen/Greger, Investment Tax Act (to be published)
Please feel free to contact us
As a tax boutique based in Munich, we support you with your tax matters.
Marius Siemen, Partner
Lukas Conrady, Partner
