Mauritius Extends DMTT Filing Deadline: More Time, But No Retreat from Pillar Two Compliance

Mauritius has taken a practical step in its implementation of the OECD’s Pillar Two framework by extending the filing and payment deadline for Domestic Minimum Top-Up Tax (“DMTT”) obligations to 30 June 2026.

While the extension may appear administrative at first glance, it signals something more important: Mauritius is actively moving from policy adoption to operational implementation of the global minimum tax regime. For multinational enterprise (“MNE”) groups with operations in Mauritius, the message is clear, Pillar Two compliance is now a live issue, not a future consideration.

The Mauritius Revenue Authority (“MRA”) announced the extension through a Communiqué issued on 26 April 2026. The extension applies where the statutory filing and payment deadline would otherwise have fallen between 1 April 2026 and 29 June 2026. In those cases, taxpayers now have until 30 June 2026 to submit DMTT returns and settle any related tax liability.

Although limited in duration, the extension reflects the growing complexity associated with Pillar Two compliance and the practical challenges faced by both taxpayers and tax administrations globally.

Mauritius and the Global Minimum Tax Framework

Mauritius formally introduced a Qualified Domestic Minimum Top-Up Tax as part of its implementation of the OECD/G20 Inclusive Framework’s Pillar Two rules.

The DMTT is designed to ensure that large multinational groups pay an effective minimum tax rate of 15% on profits arising in Mauritius before another jurisdiction can impose a top-up tax under the Income Inclusion Rule (“IIR”) or Undertaxed Profits Rule (“UTPR”).

In practical terms, the DMTT allows Mauritius to retain taxing rights over low-taxed profits generated within its jurisdiction rather than ceding those rights to foreign tax authorities.

This forms part of a broader global shift in international taxation. More than 140 jurisdictions participating in the OECD Inclusive Framework have committed to implementing Pillar Two measures aimed at addressing base erosion and profit shifting by large multinational groups.

Like many international financial centres, Mauritius has had to balance two competing objectives:

• remaining an attractive investment jurisdiction; and
• aligning with rapidly evolving international tax standards.

The introduction of the DMTT reflects Mauritius’ attempt to maintain that balance while protecting its domestic tax base and preserving treaty credibility.

Who is affected?

The DMTT applies to Mauritius resident entities that form part of an in-scope MNE group. Broadly, this includes multinational groups with consolidated annual revenue of at least EUR 750 million in at least two of the previous four fiscal years.

The rules apply from years of assessment commencing on or after 1 July 2025 and are relevant for fiscal years ending on or after 1 January 2025.

Under the Income Tax Act, a designated entity within the group is responsible for:

• calculating the DMTT liability;
• filing the DMTT return; and
• settling any top-up tax payable.

The statutory deadline is generally 15 months after the end of the relevant fiscal year.

Why the extension matters

While the extension itself is relatively short, it is significant for several reasons.

1. Pillar Two compliance is operationally demanding

The OECD’s Pillar Two framework introduces one of the most complex international tax compliance exercises in recent years.

Groups must gather and reconcile large volumes of financial, tax and jurisdictional data, often across multiple territories and reporting systems.

Key challenges commonly include:

• identifying in-scope entities;
• calculating jurisdictional effective tax rates;
• applying deferred tax adjustments;
• assessing safe harbour eligibility;
• aligning accounting standards across jurisdictions; and
• coordinating group-wide reporting obligations.

For many groups, this requires entirely new internal governance and data management processes.
The extension therefore appears to acknowledge that taxpayers and advisers are still navigating practical implementation issues.

2. Tax administrations globally are still refining processes

Mauritius is not alone in facing implementation challenges. Around the world, tax authorities continue to issue administrative guidance, update filing systems and clarify interpretative questions relating to Pillar Two compliance.

Many jurisdictions introducing DMTTs or related Pillar Two measures have experienced delays in system readiness, reporting guidance and taxpayer onboarding.

Against this backdrop, the MRA’s extension can be viewed as a pragmatic transitional measure rather than a relaxation of enforcement intent.

3. The focus is shifting from legislation to enforcement

Over the past two years, much of the international tax discussion around Pillar Two focused on legislative adoption.

That phase is now rapidly giving way to operational compliance and enforcement.

Tax authorities are increasingly concerned with whether groups:

• have appropriate data systems in place;
• can substantiate effective tax rate calculations;
• have identified exposure correctly; and
• are capable of producing contemporaneous supporting documentation.

In this environment, filing extensions should not be interpreted as reduced scrutiny. If anything, they highlight the expectation that taxpayers use the additional time to ensure accuracy and completeness.

Practical considerations for multinational groups

For affected groups with Mauritius operations, several practical considerations arise.

Assess readiness early

Groups should not wait until the revised deadline approaches before assessing their DMTT exposure.

Early-stage reviews should include:

• confirmation of whether the group falls within scope;
• identification of the designated filing entity;
• review of Mauritius effective tax rate calculations;
• assessment of available safe harbours; and
• reconciliation of accounting and tax data.

Review governance and documentation

Pillar Two compliance is heavily documentation-driven.

Groups should ensure that calculations, assumptions and adjustments are appropriately supported and capable of withstanding future review or audit.

This is particularly important given the technical complexity of the rules and the likelihood of increased tax authority scrutiny globally.

Consider interaction with wider group reporting

Mauritius DMTT obligations should also be assessed alongside broader Pillar Two reporting requirements, including:

• GloBE Information Returns (“GIRs”);
• Country-by-Country Reporting (“CbCR”); and
• transfer pricing documentation.

Consistency across these reporting frameworks will become increasingly important.

Our take

The extension to 30 June 2026 offers affected taxpayers additional time, but it should not be mistaken for a delay in Mauritius’ commitment to Pillar Two implementation.

On the contrary, the move reinforces that Mauritius is actively embedding itself within the global minimum tax framework and preparing for long-term enforcement of the rules.

For multinational groups, the key issue is no longer whether Pillar Two will apply, but whether internal systems, governance structures and compliance processes are sufficiently prepared for a significantly more data-intensive and transparent tax environment.

As implementation accelerates globally, proactive preparation will be critical. The groups best positioned for the new regime are likely to be those that treat Pillar Two not merely as a tax calculation exercise, but as a broader governance and operational challenge requiring coordination across finance, tax, legal and technology functions.