Substance Over Form in International Tax: OECD BEPS, Treaty Shopping, and Banking Implications

The principle that tax arrangements should be assessed by reference to their economic substance rather than their legal form — the substance-over-form doctrine — has moved from a domestic judicial anti-avoidance principle to the foundational concept of modern international tax law. The OECD's Base Erosion and Profit Shifting (BEPS) project, launched in 2013 and resulting in the 15 BEPS Action Plans adopted by the G20, institutionalised substance requirements across international tax treaty law, transfer pricing, controlled foreign company legislation, and hybrid mismatch rules. Understanding how substance-over-form principles operate in international tax, and what practical substance requirements must be satisfied for offshore structures to access the treaty benefits they are designed to use, is essential for any adviser structuring cross-border holding arrangements.

BEPS Action 6: Treaty Shopping and the Principal Purpose Test

BEPS Action 6 — Preventing the Granting of Treaty Benefits in Inappropriate Circumstances — addressed the problem of treaty shopping: the practice of routing income through an intermediate entity in a jurisdiction that has a favourable tax treaty with the source country, without the intermediate entity having genuine economic activity in that jurisdiction. The BEPS Action 6 report (released in 2015, incorporated into the OECD Model Tax Convention in 2017) introduced two key countermeasures: the Limitation on Benefits (LOB) rule and the Principal Purpose Test (PPT).

The Principal Purpose Test (PPT) — now incorporated as Article 7(1) of the OECD Model Tax Convention and implemented in treaties updated through the Multilateral Convention to Implement Tax Treaty-Related Measures to Prevent BEPS (MLI, in force from 2018) — provides that a treaty benefit shall not be granted if it is reasonable to conclude, having regard to all relevant facts and circumstances, that obtaining that benefit was one of the principal purposes of an arrangement or transaction. The PPT is an objective test, not a subjective one: it does not require the tax authority to prove that tax avoidance was the sole or dominant purpose, only that obtaining the treaty benefit was one of the principal purposes of the arrangement.

The practical consequence for offshore holding structures is significant. A Netherlands holding company interposed between a BVI parent and a developing country operating subsidiary purely to access the Netherlands' extensive bilateral investment treaty and tax treaty network — with the Netherlands holding company having no economic substance beyond a registered office — risks PPT challenge in the source country. The treaty benefit (reduced withholding tax on dividends or capital gains) may be denied if the source country's tax authority concludes that access to the Netherlands treaty was a principal purpose of the interposition, and the Netherlands company lacks genuine substance to justify the treaty position independently of the tax benefit.

The EU Anti-Tax Avoidance Directives

The EU has implemented substance-over-form principles through the Anti-Tax Avoidance Directive series. ATAD 1 (Directive 2016/1164/EU) addressed: interest limitation rules (capping deductible interest at 30% of EBITDA), exit taxation (taxing unrealised gains when assets leave the EU), general anti-abuse rules (a substance-over-form provision requiring EU member states to deny tax benefits for arrangements lacking genuine economic substance), controlled foreign company rules (including offshore subsidiaries' passive income in the parent's taxable base), and hybrid mismatch rules. ATAD 2 (Directive 2017/952/EU) extended the hybrid mismatch rules to arrangements with third countries.

The General Anti-Abuse Rule (GAAR) in Article 6 of ATAD 1 requires EU member states to disregard arrangements or series of arrangements which, having been put in place for the main purpose or one of the main purposes of obtaining a tax advantage that defeats the object or purpose of applicable tax law, are not genuine having regard to all relevant facts and circumstances. An arrangement is non-genuine to the extent that it is not put in place for valid commercial reasons which reflect economic reality. This is a broad statutory substance-over-form provision that EU member states' tax authorities can apply to offshore structures routed through EU entities.

The Unshell Directive (ATAD 3)

The proposed ATAD 3 — the European Commission's Directive on preventing the misuse of shell entities for tax purposes (COM/2021/565), referred to as the Unshell Directive — would require EU-resident companies with primarily passive income and mobile assets to satisfy minimum substance indicators to access EU tax benefits (treaty benefits, parent-subsidiary directive exemptions, interest and royalties directive exemptions). Companies failing to meet substance indicators (local employees, own premises, own bank accounts, non-outsourced board decisions) would be presumed to be shell entities and would be denied the relevant EU tax benefits, with information about the entity's failing reported to the tax authority of the beneficial owner's member state.

ATAD 3 has been subject to significant debate in the EU Council and has not yet been adopted in its original form. However, the direction of travel is clear — EU member states are moving toward minimum substance requirements for EU-resident entities seeking to access EU Directive benefits, aligning the onshore EU framework with the offshore economic substance legislation that already applies in BVI, Cayman, and similar jurisdictions. Advisers structuring EU holding companies must anticipate that the ATAD 3 framework, or a modified version, will ultimately be enacted and must design substance into EU holding structures from the outset.

Substance Requirements and Banking Access

The convergence of tax authority substance requirements and banking partner KYC expectations around economic substance has created a unified practical standard for international holding structures. Structures with genuine economic substance — local employees performing the core income-generating activities, resident directors with active decision-making authority, physical office space, documented board processes — satisfy both the tax substance test for treaty access and the banking partner's KYC substance expectations. Structures created solely for tax or regulatory arbitrage, without genuine activity in the jurisdiction of incorporation, fail both standards simultaneously.

The implication for offshore structure design is that substance-over-form compliance should be treated as an integrated commercial requirement — neither purely a tax compliance matter nor purely a banking access matter, but a unified standard for legitimate international structuring. Offshore holding companies with genuine commercial rationale, real local presence, and transparent beneficial ownership are the structures that will maintain both treaty access and banking relationships in the post-BEPS international tax environment.