Having tax transparency is getting more important and enforced by more and more countries around the world. To deal with tax evasion, OECD has developed an Automatic Exchange of Information (AEOI) standard. The implementation of this standard differs among countries. In this study, we explore factors explaining the differences between two information sharing arrangements in implementing the AEOI standard. In both cases, the information sharing architecture and the accompanying governance arrangement are investigated. The findings of the exploratory study show that the differences are influenced by available IT capabilities, interoperability, trust among information sharing partners, power difference, inter-organizational relationship, and perceived benefits of implementing such arrangements. Ten propositions are derived explaining the differences which can be tested in further research.