EU Tax Observatory findings and domestic enforcement measures point to persistent gaps despite stronger transparency tools
Estimates synthesized by the EU Tax Observatory and related studies suggest that a significant share of Greek wealth remains outside the country’s tax system, part of a broader pattern that continues to limit public revenue.
Research associated with the Observatory and economists such as Gabriel Zucman has estimated that a substantial share of global household wealth is held in offshore jurisdictions, amounting to trillions of dollars beyond the reach of domestic tax authorities. More recent estimates from the EU Tax Observatory place that share closer to 10 to 12 percent of global GDP.
Within the European Union, residents are estimated to hold around €1.5 trillion in assets abroad, based on the most recent comprehensive EU-wide estimate, contributing to tens of billions of euros in lost tax revenue each year.
In relative terms, Greece stands out within Europe. Estimates cited in recent EU Tax Observatory research suggest that offshore wealth linked to Greece may amount to roughly 80% of the country’s GDP, among the highest levels in the European Union, according to the Atlas of the Offshore World. Such figures point to the scale of assets held abroad relative to the size of the domestic economy, a pattern that became more visible during the financial crisis.
For Greece, the exact share is difficult to isolate. Assets held through foreign structures or accounts are, by design, hard to trace. What can be measured more clearly is the gap between declared income and actual wealth. A 2016 diaNEOsis study synthesizing earlier academic research estimated that Greece’s broader tax evasion ranged between 6% and 9% of GDP, though those figures include more than undeclared foreign assets.
Research associated with Zucman and other tax scholars has consistently shown that hidden wealth remains difficult for tax authorities to detect and tax fully, even as international transparency improves.
Greek authorities say enforcement has strengthened in recent years. The Independent Authority for Public Revenue has expanded digital reporting, cross-checks, and uses international data exchanges to identify undeclared foreign accounts. Earlier cross-checks using international data exchanges have already shown measurable results, with one documented case prompting 7,647 additional tax returns from Greek taxpayers with previously undeclared income.
Participation in the OECD’s Common Reporting Standard has also changed how information moves across borders. The system, developed by the OECD in 2014 and implemented in phases beginning in 2017, allows Greek tax authorities to receive financial account data from more than 80 jurisdictions each year and match foreign holdings with domestic filings. In practice, this has made concealment more difficult, particularly for straightforward accounts, though more complex ownership structures can still obscure the true location of assets.
The issue remains politically sensitive in Greece. During the years of austerity, tax compliance became a central point of public debate, as wage earners and small businesses faced increased scrutiny while concerns about uneven enforcement persisted.
That tension has not fully disappeared. When income and assets are not taxed evenly, the burden shifts toward those whose earnings are already visible to the state. For households still shaped by the post-crisis economy, the question is not only how much revenue is lost, but how fairly the system operates.
Policy analysts argue that closing the gap will require stronger international coordination, clearer ownership rules, and continued pressure on jurisdictions with limited disclosure, alongside domestic enforcement efforts.
The scale of wealth held abroad is difficult to measure precisely, and much of it is likely to remain beyond the reach of any single tax authority.
What is clearer is the implication: as long as a share of income and assets stays outside the system, the limits of enforcement will continue to shape both public revenue and public trust in how that system works.