The use of evidence obtained during criminal proceedings by the tax authorities repeatedly raises delicate constitutional issues. In its decision of 23 April 2025 (I B 51/22), the Federal Fiscal Court (BFH) clarified: If digital evidence — here, a hard drive — is handed over to the tax office without the mandatory prior screening by the public prosecutor’s office, this violates the fundamental right to informational self-determination and results in an exclusion of evidence.
Facts of the Case
In the case at hand, a Cypriot company was suspected by the tax office of having its actual place of management in Germany. This suspicion was mainly based on emails and documents stored on a hard drive belonging to a general partnership (A-OHG), which had been seized by the public prosecutor’s office during a criminal investigation unrelated to tax matters (insider trading).
Without performing the legally required screening, the public prosecutor’s office handed the entire hard drive over to the tax auditor. The auditor analyzed all data, including private correspondence, and based the tax assessment — involving an assumption of unlimited tax liability in Germany — on this material.
Legal Analysis
Basic Principle: Use of Information Obtained in Criminal Proceedings
According to Section 393 (3) sentence 1 of the Fiscal Code (AO), information lawfully obtained during criminal investigations may generally be used for tax purposes. This broad permission also applies to so-called “chance findings”.
Limitation: Obligation to Perform Prior Screening (§ 110 German Code of Criminal Procedure)
However, the admissibility of such information is conditional upon the public prosecutor performing a proper prior screening of seized documents or data media to separate relevant from irrelevant information. This duty, anchored in Section 110 of the German Code of Criminal Procedure (StPO), safeguards the fundamental right to informational self-determination and prevents indiscriminate “data fishing”.
In this case, no such screening took place. The hard drive was handed over in full, without regard to the protection of private information. The BFH held that this constituted a violation of constitutional rights that cannot be cured retroactively in the tax procedure.
Qualified Exclusion of Evidence
While procedural mistakes do not always lead to an exclusion of evidence in tax matters, the BFH reaffirmed that a “qualified” exclusion applies when the manner of obtaining the evidence infringes upon a constitutionally protected sphere. The court found this threshold to be crossed here.
Consequently, the lower court’s decision, which had relied on the data, was quashed and remitted. The tax court must now re-evaluate the matter without considering the unlawfully used hard drive data.
Practical Implications
This decision underlines the primacy of constitutional rights: Even in tax proceedings, investigating authorities may not bypass safeguards by transferring unscreened data en masse. Tax auditors must not act as surrogate prosecutors with unlimited access to private data. For taxpayers, the ruling reinforces privacy protections and emphasizes that procedural rights must be actively asserted when confronted with seizures and data handovers.
Conclusion: The BFH draws a clear line: No screening, no handover — and no admissibility. This protects taxpayers from excessive data exploitation unrelated to the original criminal investigation and maintains the balance between effective taxation and fundamental rights. The ruling is a strong reminder that even in complex cross-border cases, due process must not be sacrificed for investigative convenience.
Our law firm specialises in criminal defence, white-collar crime and IT law / technology law. Note our activity in digital evidence in IT security and software law.
- Understanding cyber diplomacy as a strategic necessity - 19. June 2025
- Israel and Iran: Cyber Espionage, Cyber Warfare and Cyber Defense in Comparison - 19. June 2025
- Israel: Cyber Espionage, Cyber Warfare and Cybersecurity - 19. June 2025