G20 leaders used the April 2009 London Summit to push for stronger action against tax havens and cross-border tax evasion. The OECD began publishing lists that categorized jurisdictions by their commitment to internationally agreed tax transparency standards. This created a political starting point for later OECD-led transparency and anti-avoidance measures.
The amended Convention on Mutual Administrative Assistance in Tax Matters (often called the "MAC") entered into force, expanding the legal foundation for countries to cooperate on tax matters. It supports multiple tools, including information exchange and assistance in collection, and made it easier for more jurisdictions to join. This legal backbone later supported automatic exchange arrangements like the Common Reporting Standard.
After 2009, the OECD Global Forum increased monitoring through peer reviews of the "exchange of information on request" standard (tax authorities requesting information from each other for a specific case). These reviews examined whether jurisdictions could identify owners, access bank information, and respond in practice. The peer-review process became a key lever for pressuring offshore centers to change laws and administrative practices.
The OECD released its BEPS (Base Erosion and Profit Shifting) Action Plan, setting out 15 actions to curb corporate tax strategies that shift profits to low- or no-tax jurisdictions. The plan responded to G20 concerns that gaps between countries’ rules were enabling aggressive tax avoidance. It became the roadmap for later transparency and treaty-related reforms, including measures affecting offshore structures.
The OECD Council approved the Common Reporting Standard (CRS), a global framework for automatic exchange of financial account information between tax authorities. Under CRS, financial institutions collect specified account data and jurisdictions exchange it annually, shifting enforcement away from purely "on request" cooperation. CRS directly targeted offshore wealth concealment by increasing the likelihood that undeclared foreign accounts would be detected.
Dozens of jurisdictions signed the CRS Multilateral Competent Authority Agreement (CRS MCAA) in Berlin, creating a common legal arrangement to implement CRS exchanges. This step translated the CRS standard into operational government-to-government commitments, including timelines for first exchanges. It helped convert political support for transparency into a system designed to work at large scale.
The OECD released final BEPS reports, including Action 13 on Country-by-Country (CbC) reporting for large multinational enterprises. CbC reporting requires a standardized template showing where a group’s profits, taxes, and indicators of activity are located, which helps tax authorities spot profit shifting. While not public by default, it strengthened cross-border enforcement by improving information available to governments.
The Panama Papers—published in early April 2016—exposed extensive use of offshore entities and sparked public and political pressure for stronger transparency and enforcement. The revelations highlighted how shell companies and secrecy jurisdictions could be used to obscure asset ownership and income. This moment reinforced demand for measures like CRS and beneficial ownership reforms to reduce hidden offshore wealth.
The OECD/G20 Inclusive Framework on BEPS held its inaugural meeting in Kyoto, bringing a much larger group of countries and jurisdictions into BEPS implementation "on an equal footing." The Inclusive Framework created a governance structure for peer reviews of BEPS minimum standards and ongoing rule development. This widened the reach of anti-avoidance and transparency norms beyond OECD members, including many offshore and developing jurisdictions.
Negotiators concluded and adopted the BEPS Multilateral Instrument (MLI), designed to update many bilateral tax treaties more quickly than renegotiating each treaty one by one. The MLI supports anti-treaty-shopping rules (rules aimed at preventing improper treaty benefits) and other treaty-related BEPS measures. This helped close treaty gaps that could facilitate routing income through offshore hubs.
A first wave of jurisdictions signed the BEPS MLI in Paris, signaling political commitment to implement treaty-related anti-avoidance measures at scale. Signing did not itself change treaties immediately, but it started the process of ratification and treaty-by-treaty matching. Over time, this mechanism aimed to reduce opportunities for offshore structures that depend on weak treaty provisions.
The first CRS automatic exchanges occurred among early-adopting jurisdictions, moving from commitments to live data sharing. In practice, this meant tax authorities began receiving standardized information about offshore financial accounts held by their residents. This shift materially increased the risk of detection for undeclared offshore wealth and supported enforcement actions and voluntary disclosure programs.
The BEPS MLI entered into force, enabling it to start taking legal effect for jurisdictions that had ratified it. As parties activated the MLI for specific "covered tax agreements," treaty changes began to apply on set effective dates. This marked a transition from negotiated standards to enforceable treaty updates aimed at limiting cross-border tax avoidance routes.
The OECD released revisions to the BEPS Action 5 minimum standard for the spontaneous exchange of information on certain tax rulings. The update reflected nearly a decade of experience, with the OECD reporting tens of thousands of exchanges tied to identified rulings since BEPS began. It also set a path for updated peer reviews and technical standards, aiming to further reduce secrecy around preferential rulings often linked to offshore tax planning.
OECD, BEPS, and international tax transparency measures against offshore wealth (2009–2023)