Navigating tax disputes and litigation in Belgium & Luxembourg

Focusing on recent developments, the guide offers insights into processes, timescales and costs involved in resolving complex tax matters.

Belgium

Belgian tax procedures vary depending on the type of tax. A common feature, however, is that there are generally no fees payable to the tax authorities or the courts. Taxpayers may represent themselves before these bodies, allowing them to avoid legal counsel fees.

Special services have been established within the tax authorities to serve as intermediaries between taxpayers and the assessment services. The Ruling Commission was created to help prevent disputes, while the Tax Conciliation Service was established to assist taxpayers already involved in a dispute.

The Act of 20 November 2022 significantly extended the investigation and assessment periods with effect from assessment year 2023. However, a new bill is expected to reduce these periods again, meaning that most of the extensions provided by the 2022 Act will no longer apply.

Luxembourg

In 2024, the number of publicly reported direct tax litigation cases in Luxembourg continued to decline. Both the Administrative Tribunal (first-instance court for most direct tax matters) and the Administrative Court (appeal court) issued significantly fewer judgments compared to previous years -reinforcing a trend that began in 2020. Between 2022 and 2024, the total number of tax-related judgments dropped by more than 40%.

Considering the numerous legal changes in the past 8 to 10 years—and further adjustments expected, such as the implementation of Pillar Two rules—litigation may increase due to the growing complexity of the tax framework and the declining relevance of tax rulings. However, the recent reduction in judgments may signal a shift toward greater legal certainty, supported by more detailed parliamentary documentation and administrative guidance from the tax authorities.

In addition to domestic litigation, Luxembourg also continues to engage in EU-level tax controversy. Recent examples include cases related to the DAC6 Directive (mandatory disclosure rules), which underline the broader European implications of Luxembourg's tax framework.

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