Summary (3 bullet points)
- The Belgian tax authorities have issued an administrative circular on 1 April 2026 confirming the retroactive application of the expanded expat regime to remunerations paid or granted as from 1 January 2025. [tiberghien.com]
- The circular confirms that existing remuneration structures may be adjusted retroactively, with changes allowed up to 30 June 2026, creating opportunities for employers already applying the regime. [tiberghien.com]
- While the tax administration endorses the widened regime, divergences with the social security (RSZ) position remain, potentially leading to practical and compliance challenges. [tiberghien.com]
Article
On 1 April 2026, the Belgian tax administration published an administrative circular clarifying the implementation and temporal scope of the expanded special tax regime for inbound taxpayers and researchers (expat regime). The circular provides long-awaited confirmation that the legislative changes introduced at the end of 2025 apply retroactively to remuneration paid or granted from 1 January 2025, thereby strengthening the attractiveness of the regime for both employers and qualifying individuals. [tiberghien.com]
Background: Expansion of the Expat Regime
The expanded expat regime follows legislative amendments adopted in late 2025 with the aim of making Belgium more competitive in attracting international talent. Key changes include an increase in the tax-free allowance for costs proper to the employer from 30% to 35% of the annual gross salary, the abolition of the EUR 90,000 cap, and—specifically for inbound taxpayers—the reduction of the minimum gross annual remuneration threshold from EUR 75,000 to EUR 70,000. These measures apply both to inbound taxpayers and to inbound researchers, except where specific rules apply. [tiberghien.com]
Retroactive Application Confirmed
The circular explicitly confirms that these measures apply retroactively as of 1 January 2025. In this context, the tax authorities distinguish two main situations. For individuals who already benefited from the expat regime in 2025, employers may retroactively adapt remuneration structures to reflect the more favourable conditions. Importantly, such retroactive adjustments are permitted until 30 June 2026, offering a limited window for implementation. [tiberghien.com]
The circular further clarifies that pro-rata calculations for the minimum remuneration threshold must be based on the new EUR 70,000 threshold, while the pro-rata application of the former EUR 90,000 cap becomes irrelevant due to its abolition. [tiberghien.com]
Interaction with Social Security Rules
A critical point highlighted by the circular is the lack of alignment with social security law. While the tax authorities fully apply the expanded regime, the National Social Security Office (RSZ) does not follow the increase to 35% nor the removal of the EUR 90,000 cap, except for its acceptance of the lowered EUR 70,000 threshold. For social security purposes, the previous limits therefore remain relevant, creating a split treatment between tax and social security. This divergence may result in administrative complexity and increased compliance risks for employers. [tiberghien.com]
Practical Implications for Employers
The circular confirms that the expanded expat regime creates clear planning opportunities, particularly for employers that already apply the regime and can still restructure remuneration retroactively before the June 2026 deadline. However, the practical impact requires careful case-by-case analysis, given the unresolved questions on the precise scope of the deadline and the continuing discrepancy between tax and social security treatment. Employers are therefore advised to assess payroll, documentation, and compliance implications carefully before implementing retroactive changes. [tiberghien.com]
Source:
- Tiberghien – Circulaire bevestigt retroactieve toepassing verruimd expat statuut (2 April 2026) [tiberghien.com]
