The standard of foreseeable relevance in privacy enhanced tax information exchange: case study on FCInet ma³tch technology

Huiskers-Stoop, E.A.M.; Hasen Nezhad Nisi, T.; Mosquera Valderrama, I.J.; Mosna, A.; Ouwerkerk, J.W. (2025)

External research report

Since the turn of the century, the exchange of information has become a vital tool in the fight against tax evasion and aggressive tax avoidance. A strong information position of governments worldwide is needed to tackle tax fraud, financial crime, and other crimes that undermine society. At the same time, these governments must uphold and safeguard public values, in particular the protection of taxpayer data and privacy. This creates a challenging dual role for government organisations that collect and use data for the proper execution of their work.

The Forum of Heads of Tax Crime Investigation, held under the auspices of the Organisation for Economic Co-operation and Development (OECD), recognised this duality and initiated the FCInet-platform, which houses a built-in privacy enhancing technology named “ma³tch”, to meet this challenge. FCInet can be described as a decentralised government computer system that enables public administrations from different countries to cooperate and exchange information on a bilateral basis, while respecting each other's local autonomy.

The ma³tch technology generates a filter from local data sources that are autonomously selected by the sending organisation. This filter, created using a sophisticated set of algorithms, is then shared with one or more peer organisations, also selected by the sender. The receiving organisation can anonymously check whether (selected) keys from its own database are present in the filter. This privacy-enhancing approach allows organisations to identify potential matches between databases, so-called “hits”, without revealing personal data unless further verification validates the hit and a follow-up request for tax information exchange can be initiated.

Collecting, combining and analysing information offers advantages, but it can also easily breach on the privacy of citizens when it comes to personal data. Organisations that use the technology must comply with the legal requirements for international cooperation and information exchange, and the associated data protection and privacy laws. Article 26 of the OECD Model Tax Convention on Income and Capital provides a legal foundation for the bilateral international exchange of tax information. It outlines three methods of exchange: spontaneous, automatic, and upon request. Central to all three, is the standard of foreseeable relevance, which requires that any data exchanged must be potentially useful for the tax enforcement purposes of the receiving state.

The study, commissioned by the Board of FCInet, maps the meaning of the principle of foreseeable relevance in relation to the application of the technology, identifies differences in interpretation between countries involved in the study, and highlights some challenges in the protection of personal data. 

• Tax information exchange
• Foreseeable relevance
• Privacy and data protection

• All authors: Huiskers-Stoop, E.A.M.; Hasen Nezhad Nisi, T.; Mosquera Valderrama, I.J.; Mosna, A.; Ouwerkerk, J.W.
• Awarding Institution: Institute of Tax Law and Economics, Faculty of Law, Leiden University
• Date: 2025-09-18