Belgium: Boundaries of tax investigations and data requests (Court of Appeal decision)

The Court of Appeal of Ghent on June 24, 2025, issued a comprehensive decision further delineating the principles governing the Belgian tax authorities’ rights to request information and the corresponding obligations of taxpayers, particularly in the context of digital data and mailboxes used for both private and business purposes.

The court reiterated its longstanding position that so-called “fishing expeditions”—searches for incriminating data without concrete cause—are not permitted. However, the court confirmed that the tax administration is entitled, in the first instance, to determine which mailboxes and digital data are relevant for tax purposes. Only by unsealing the data can the administration properly assess its relevance. Consequently, taxpayers cannot rely on the mixed nature of their mailboxes to limit the administration’s investigative powers.

Nonetheless, the court stressed that the administration must act “with the greatest possible caution” when handling private correspondence and must have concrete indications of relevance before requesting access to broad datasets. In addition, the Court recommended that the administration use precisely selected search terms tailored to the focus of the investigation when filtering released data. The court also reaffirmed that correspondence between taxpayers and professionals bound by professional secrecy (such as lawyers, accountants, and notaries) is protected and cannot be accessed by the tax authorities.

Read a September 2025 report prepared by the KPMG member firm in Belgium