Spain has taken a practical step forward in applying the Complementary Tax (IC), internationally known as the Global Minimum Tax or OECD/G20 Pillar II.

The Tax Administration has marked a key milestone, moving from theory to practice. This is reflected in the recent publication in the Official State Gazette (BOE) of two important regulations:

  • Declaration and Self-Assessment Forms: Approval of forms 240, 241, and 242 (Order HAC/1198/2025), essential for reporting and, if applicable, self-assessing the tax.
  • Information Exchange Framework: Publication of the Multilateral Agreement for automatic GloBE information exchange (BOE-A-2025-21920), crucial for cross-border coordination.

These measures mark the start of the operational phase for a system that sets a minimum effective tax rate of 15% for multinational groups with consolidated revenues over €750 million.

Who is affected and what does it mean?

The IC changes the roles within multinational groups, especially for Spanish subsidiaries of foreign parent companies. While the main tax responsibility lies with the Ultimate Parent Entity (UPE) abroad (through the IIR – Income Inclusion Rule), Spanish subsidiaries also play an active role:

  • Groups with a parent in Spain: need to calculate and consolidate the overall effective tax. If any jurisdiction falls below 15%, a top-up tax applies in Spain.
  • Spanish subsidiaries of European or non-EU parents: must provide detailed financial info and take part in GloBE calculations. If the parent is in a country without a similar tax, the UTPR (Undertaxed Payment Rule) may apply in Spain.
  • Parent or subsidiary in jurisdictions without a similar tax: if the parent’s country doesn’t implement Pillar II, Spain or another EU country can collect the tax for untaxed amounts. Poor planning could lead to duplicate taxation. Here, the Spanish subsidiary becomes responsible for paying the tax, not just reporting it.

For Spanish subsidiaries, Pillar II introduces several formal obligations in the coming years:

  • Form 240: identify the taxpayer, tax period, and Ultimate Parent Entity’s country/territory.
  • Form 241: informational report on the Complementary Tax, including effective rates by jurisdiction and any adjustments below 15%.
  • Form 242: self-assessment when the Spanish subsidiary owes top-up tax or UTPR adjustments.

Challenges for companies

The main challenge is not just legal or fiscal, but operational and technological:

  1. Scope and identification: define the GloBE group and reporting entity clearly.
  2. Calculation and review: adapt accounting and tax processes to calculate effective rates per jurisdiction according to GloBE rules.
  3. Systems and processes: implement systems to gather, harmonize, and present large volumes of financial data per jurisdiction, ensuring accuracy and auditability.
  4. Managing forms: make sure forms 240, 241, and 242 are correctly completed, differentiating between reporting and self-assessment, and keeping consistency with global GloBE data.

Companies also need to evaluate transitional “safe harbors,” which may temporarily exempt them from filing or paying the tax in the first years.

In practice, implementation will be gradual, requiring proactive management, tech investment, and specialized advice to navigate this new, complex aspect of international taxation.

At addwill, we provide full support to comply with these obligations and analyze your company’s specific situation. Contact us via the form to learn more.