Belgium: Side-by-side package does not affect pending UTPR proceedings (Constitutional Court decision)
The challenge to Belgium’s UTPR provisions will continue pending the CJEU’s consideration of a preliminary question.
The Belgian Constitutional Court (BCC), on September 24, 2026, held that the planned transposition of the side-by-side (SbS) package into Belgian law does not affect proceedings challenging Belgium’s undertaxed profits rule (UTPR) provisions. The appeal was filed by a U.S. nonprofit organization established under Wyoming law seeking annulment of Articles 35 and 36 of the Belgian minimum tax law.
The BCC previously referred a question to the Court of Justice of the European Union (CJEU) concerning whether certain UTPR provisions of Directive (EU) 2022/2523 infringe European rights and legal principles.
The BCC held that draft legislation implementing the SbS package is insufficient to deprive the applicant of its interest in seeking annulment. It also noted that certain Belgian subsidiaries of U.S. companies could remain subject to the UTPR top-up tax, including potentially for tax year 2025.
The proceedings will therefore continue, with the CJEU expected to address the preliminary question referred by the BCC.
Read a September 2026 report prepared by the KPMG member firm in Belgium