What is Multilateral Instrument (MLI)?

How it works

The Multilateral Instrument — formally the Multilateral Convention to Implement Tax Treaty Related Measures to Prevent Base Erosion and Profit Shifting — was signed in June 2017 by ~70 jurisdictions and has since grown to 100+ signatories. It went into force from 1 July 2018 onward (varying by signatory).

The MLI's purpose: implement the treaty-related BEPS Actions (Actions 2, 6, 7, 14) across thousands of bilateral tax treaties simultaneously, without each country having to renegotiate every bilateral treaty individually.

Mechanism: signatories notify the OECD which of their bilateral treaties they want covered ("Covered Tax Agreements") and which MLI provisions they accept. When two countries' positions match on a treaty and on a provision, the MLI modifies that bilateral treaty automatically. The treaty isn't replaced — it's overlaid by the MLI on the matched provisions.

Key MLI provisions

Mandatory minimum standards (signatories must accept):

• Treaty preamble update (Article 6): clarifies that treaties are not intended to create opportunities for tax evasion or avoidance.
• Anti-abuse rules (Article 7): default is the Principal Purpose Test (PPT), with optional Limitation on Benefits (LOB) addition.
• Improved Mutual Agreement Procedure (MAP) (Article 16).

Optional provisions (signatories opt in or reserve):

• Hybrid mismatch arrangements (Articles 3-5).
• Permanent establishment definitions broadened (Articles 12-15) — including artificial avoidance via dependent agents and commissionaire arrangements.
• Arbitration for unresolved MAP cases (Articles 18-26) — opt-in.

How to read a treaty post-MLI

The original bilateral treaty + the MLI form a composite. To know what applies between, say, France and Italy:

1. Find the original France-Italy bilateral tax treaty.
2. Check the MLI Synthesised Texts (OECD or national tax-authority publications) showing the matched modifications.
3. Read the treaty clause-by-clause noting where MLI overrides apply.

For example: France-Italy treaty pre-MLI had certain dividend WHT mechanics; post-MLI, PPT is now layered as an anti-abuse rule on top, modifying which structures qualify for treaty benefits.

Notable non-signatories

• United States — has not signed the MLI. US bilateral treaties retain US-specific LOB clauses without PPT (though recent US Model Treaty post-2016 includes some main-purpose-style language).
• Brazil — limited MLI adoption.
• A handful of smaller jurisdictions.

For US-treaty cases, MLI provisions don't apply automatically; check the actual US-X treaty.

Examples

• Pre-MLI: French resident receives UK dividend through a Cypriot SPV. Cyprus-UK treaty 0% WHT applies because the Cypriot SPV is a Cyprus tax resident.
• Post-MLI: Same setup. UK-Cyprus treaty has been modified by MLI to include PPT. The SPV has no commercial purpose other than treaty access. UK HMRC denies the WHT reduction under PPT — UK domestic 20% WHT applies on the dividend.

Common mistakes

• Treating treaties as static. Most major treaties have been modified by MLI since 2018. Pre-MLI guides describe outdated positions.
• Assuming MLI applies everywhere. US, Brazil, some others haven't signed. Check the specific treaty pair.
• Skipping the synthesised text. Reading just the original bilateral treaty misses the PPT layer and other MLI modifications.
• Confusing MLI with treaty renegotiation. MLI overlays existing treaties without replacing them. The bilateral treaty text remains in force; MLI just modifies specific clauses.