On 15 July 2014 the OECD published the Standard for Automatic Exchange of Financial Account Information in Tax Matters, also known as the Common Reporting Standard or CRS. Since then 102 jurisdictions have committed to its implementation in time to commence exchanges in 2017 or 2018. With exchanges under the CRS having now commenced amongst almost 50 jurisdictions there has been a major shift in international tax transparency and the ability of jurisdictions to tackle offshore tax evasion. At the same time, information from academic studies and media leaks, combined with more recent information collected through compliance activities of a number of tax administrations, as well as the results from the OECD’s disclosure initiative demonstrate that professional advisers and other intermediaries continue to design, market or assist in the implementation of offshore structures and arrangements that can be used by non-compliant taxpayers to circumvent the correct reporting of relevant information to the tax administration of their jurisdiction of residence, including under the CRS. The Model Mandatory Disclosure Rules for CRS Avoidance Arrangements and Opaque Offshore Structures contained in this report were approved by the Committee of Fiscal Affairs (CFA) on 8 March 2018.