Convention on Mutual Administrative Assistance in Tax Matters (MAC)

The Convention on Mutual Administrative Assistance in Tax Matters (MAC) is the most comprehensive multilateral instrument for tax cooperation and was jointly developed by the OECD and the Council of Europe. It was opened for signature in 1988, entered into force in 1995, and was fundamentally revised by a protocol in 2010, opening it to all states — not just OECD members.

The MAC forms the crucial legal foundation for the Multilateral Competent Authority Agreement (MCAA) and thus for the entire CRS mechanism. Without MAC ratification, a jurisdiction generally cannot participate in the MCAA and therefore in the automatic exchange of information under the CRS.

The MAC was developed in response to the growing need for multilateral tax cooperation and marks a paradigm shift from purely bilateral to multilateral cooperation:

• 1988: Signing of the original Convention by OECD and Council of Europe members
• 1995: Entry into force for the first contracting states
• 2010: Comprehensive revision protocol; opening to all states (not just OECD/Council of Europe); extension of instruments to automatic exchange
• 2011: Entry into force of the revised Convention
• 2014: The revised MAC becomes the foundation of the MCAA for the CRS
• 2015 onwards: Rapid accession of further jurisdictions under the BEPS Action Plan
• Today: Over 150 jurisdictions (152 as of January 2026) have ratified or signed the MAC

The MAC governs a wide range of forms of tax cooperation:

• Exchange of information on request (EOIR): Information is transmitted upon request by a tax authority
• Automatic exchange of information (AEOI): Routine transmission of information on certain income categories
• Spontaneous exchange: Forwarding of information without prior request when an authority considers it relevant to another state
• Tax examinations abroad: Participation in tax examinations in another contracting state
• Simultaneous examinations: Coordinated examinations in multiple states
• Assistance in recovery: Support for the enforcement of tax claims abroad
• Assistance in service: Support for the service of tax documents abroad

• Ratification: States must ratify the Convention and the 2010 Protocol and implement them into national law
• Confidentiality: Exchanged information is subject to the tax secrecy provisions of the receiving state
• Reciprocity (Art. 21): A state is not obliged to provide assistance beyond measures available under its own law, or that the requesting state could not provide under its own law
• Public policy: States may refuse assistance if it would violate public policy or essential state interests
• Non-discrimination: Assistance must be provided in the same manner as for that state's own taxes
• Reservations (Art. 30): States may make reservations upon accession to exclude certain forms of assistance (e.g. assistance in recovery)

3 corrections:
- effective_date wrong: 1988-04-01 instead of 1995-04-01
- History incorrectly attributes entry into force to 1988
- Summary claims entry into force 1988 instead of 1995
2 updates:
- Jurisdiction count outdated: 'over 145' instead of 'over 150'
- official_url outdated — OECD 403
2 clarifications.
2 notes.