30 June 2026: Luxembourg Entities In-Scope for Pillar Two Must Register With the Tax Authorities

Luxembourg's Pillar Two registration deadline falls on 30 June 2026. Every Luxembourg entity that is part of an in-scope multinational enterprise group — those with consolidated annual revenue of at least €750 million in two of the four preceding fiscal years — must file a Pillar Two registration with the Luxembourg tax authorities by that date. The registration is separate from the standard corporate income tax registration and includes specific information requirements set out in the implementing legislation.

What Pillar Two does

Pillar Two is the OECD/G20 Inclusive Framework's global minimum corporate tax. It imposes a 15% effective tax rate on the profits of in-scope MNE groups, jurisdiction by jurisdiction, by means of three coordinated rules: an Income Inclusion Rule, an Undertaxed Profits Rule, and a Qualified Domestic Minimum Top-up Tax. Luxembourg has implemented all three. The QDMTT, in particular, is the rule under which Luxembourg itself collects any additional top-up tax owed on Luxembourg-resident profits, ensuring the revenue stays in the jurisdiction rather than being collected by another country under IIR or UTPR.

What the registration requires

The registration form requires identification of the Luxembourg entity, identification of the ultimate parent of the MNE group, a description of the group's structure and the Luxembourg entity's role, and elections (where applicable) on safe-harbour positions. The information requirements are technical but well-documented; the 2025 guidance from the Administration des Contributions Directes set the practical bar.

Who is affected

The €750 million revenue threshold catches a meaningful share of Luxembourg's multinational footprint — large international corporates, major banking and insurance groups, and the majority of large fund-management groups, although individual investment funds are typically excluded. Luxembourg-resident entities that sit somewhere in the structure of an in-scope group must register, regardless of size.

What practitioners should be doing now

Three priorities. First, group-level confirmation of in-scope status — the threshold test is consolidated-revenue-based and applies to the entire MNE group, not the Luxembourg entity in isolation. Second, internal data collection: the calculations underlying the QDMTT, IIR and UTPR depend on data points that many groups have not previously reported on a Luxembourg-specific basis. Third, election decisions: safe-harbour and transitional elections must be considered before they are made on the registration.

The macro context

Luxembourg's strategic posture on Pillar Two has been to implement fully, on time, while maintaining the country's other competitive advantages — substance-based regimes, IP frameworks, fund tax neutrality — within the boundaries Pillar Two leaves open. The 30 June 2026 registration deadline is the first major operational gate. The first formal Pillar Two filings — the substantive top-up tax returns — will follow in 2027 for the 2026 fiscal year. The next two years will determine how much of the country's tax-policy adaptability survives in practice under the new framework.