What Is the Multilateral Instrument (MLI)?
The Multilateral Instrument (MLI) is a multilateral tax convention under which participating jurisdictions modify existing bilateral double tax treaties to add anti-abuse and dispute-resolution measures.
Also known as: MLI, BEPS Multilateral Convention.
How Multilateral Instrument (MLI) works
The Multilateral Instrument (MLI) operates alongside existing double tax treaties rather than replacing them, so a bilateral treaty changes only when both partner jurisdictions list the treaty as a covered tax agreement, ratify the convention and select compatible options under its articles. The MLI implements BEPS minimum standards on treaty abuse, generally through a principal purpose test, and on improving the mutual agreement procedure. Optional provisions, such as permanent establishment or tie-breaker changes, apply only where both parties make matching choices. The United Kingdom signed the MLI on 7 June 2017, with entry into force for the UK on 1 October 2018 and each treaty modified only after the partner ratifies.
Multilateral Instrument (MLI) vs Double Tax Treaty (DTT)
Unlike a Double Tax Treaty, which allocates taxing rights between two countries, the Multilateral Instrument creates no standalone allocation rules and instead amends covered bilateral treaties according to options both parties have matched.
Example
Illustrative example: A consultant resident in Country A receives royalties from Country B; both countries have listed their bilateral treaty under the Multilateral Instrument. The reduced withholding rate still comes from the original treaty, yet the principal purpose test added by the MLI may deny the rate where obtaining the benefit was one of the principal purposes of an arrangement.
Common misconception
Myth: Reading the original bilateral treaty text is enough to know which treaty rules apply.
Reality: The Multilateral Instrument may have modified the treaty, so the applicable text generally depends on both parties' MLI positions, ratification dates and any consolidated version published by the tax authorities.
Frequently asked questions
Does the MLI replace existing tax treaties?
The Multilateral Instrument does not replace existing tax treaties; the MLI modifies covered bilateral treaties in parallel, and each original treaty continues to apply as amended by the provisions both parties have adopted.
When does the MLI apply to a specific treaty?
The Multilateral Instrument applies to a treaty only after both jurisdictions list the treaty and ratify the MLI; in the UK, effect began on different dates for withholding taxes, Corporation Tax and Income Tax.
Related terms
- Principal Purpose Test — Main anti-abuse rule inserted by the MLI
- Base Erosion and Profit Shifting (BEPS) — OECD project which produced the MLI
- Treaty Shopping — Practice the MLI anti-abuse provisions target
- Vienna Convention on the Law of Treaties — Modifies treaties that are read under these rules
Related guides
- Tax treaties and international taxation — Background on how tax treaties allocate taxing rights
- Global tax reform and US digital nomads — Context on OECD-led international tax reform
Sources
Last verified: 2026-10-08. This entry is general information, not tax or legal advice; rules vary by country and change over time.
