Belgian multinational groups have gained an unexpected reprieve as the Federal Public Service Finance confirmed on 17 November 2025 that the **first Domestic Minimum Top-up Tax (DMTT) return now only needs to be filed by 30 June 2026, instead of 30 November 2025**.
The DMTT is Belgium’s mechanism for implementing the OECD/G20 Pillar Two global minimum tax. It requires Belgian entities belonging to large groups (consolidated turnover ≥ €750 million) to perform complex jurisdiction-by-jurisdiction top-up tax calculations and to report the results in a brand-new return. Under the original law, companies whose financial year mirrors the calendar year would have been forced to submit their first DMTT return barely five months after finalising their 2024 accounts.
![Belgium Extends Filing Deadline for New Domestic Minimum Top-Up Tax Return]()
Tax departments and Global Mobility managers had voiced concern that the tight timetable would collide with the equally new **GloBE Information Return (GIR)**, creating a compliance bottleneck at the very moment when remuneration data for highly mobile employees has to be reconciled across entities and territories. By synchronising the DMTT and GIR deadlines (both now 30 June 2026) the authorities have effectively given multinational employers an extra seven months to build the necessary data pipelines, validate shadow payrolls for expatriates and adapt internal sign-off procedures.
The breathing space is particularly welcome for HR and mobility teams because assignee compensation often drives Pillar Two effective-tax-rate calculations. Short-term business travellers and split payrolls can push qualified income between jurisdictions, so payroll accuracy and equity reconciliations will be critical. Companies are therefore urged to use the deferral to audit expatriate reporting processes, enhance data sharing between tax, payroll and mobility functions, and review global assignment policies to ensure that incentives do not trigger unintended top-up liabilities.
Practically, employers should update their compliance calendars, inform finance controllers and assignees, and liaise with software providers to adjust project timelines. Although the filing date has moved, the underlying calculations still relate to fiscal year 2024, so source data must be captured now. Ignoring the extension could leave organisations scrambling again next spring when Pillar Two safe-harbour reliefs start to phase out.
The DMTT is Belgium’s mechanism for implementing the OECD/G20 Pillar Two global minimum tax. It requires Belgian entities belonging to large groups (consolidated turnover ≥ €750 million) to perform complex jurisdiction-by-jurisdiction top-up tax calculations and to report the results in a brand-new return. Under the original law, companies whose financial year mirrors the calendar year would have been forced to submit their first DMTT return barely five months after finalising their 2024 accounts.
Tax departments and Global Mobility managers had voiced concern that the tight timetable would collide with the equally new **GloBE Information Return (GIR)**, creating a compliance bottleneck at the very moment when remuneration data for highly mobile employees has to be reconciled across entities and territories. By synchronising the DMTT and GIR deadlines (both now 30 June 2026) the authorities have effectively given multinational employers an extra seven months to build the necessary data pipelines, validate shadow payrolls for expatriates and adapt internal sign-off procedures.
The breathing space is particularly welcome for HR and mobility teams because assignee compensation often drives Pillar Two effective-tax-rate calculations. Short-term business travellers and split payrolls can push qualified income between jurisdictions, so payroll accuracy and equity reconciliations will be critical. Companies are therefore urged to use the deferral to audit expatriate reporting processes, enhance data sharing between tax, payroll and mobility functions, and review global assignment policies to ensure that incentives do not trigger unintended top-up liabilities.
Practically, employers should update their compliance calendars, inform finance controllers and assignees, and liaise with software providers to adjust project timelines. Although the filing date has moved, the underlying calculations still relate to fiscal year 2024, so source data must be captured now. Ignoring the extension could leave organisations scrambling again next spring when Pillar Two safe-harbour reliefs start to phase out.
