The Organisation for Economic Co-operation and Development (OECD) and the United Nations Development Programme (UNDP) today released the Tax Inspectors Without Borders (TIWB) Annual Report 2026, highlighting continued progress in supporting developing countries to strengthen tax systems and mobilise domestic resources to fund essential public services and economic development.
Since its launch in 2015, TIWB has delivered 165 programmes across 70 developing jurisdictions, helping raise USD 2.72 billion in additional tax revenues and secure USD 7.67 billion in tax assessments. Its hands-on approach, embedding experienced tax experts within host tax administrations, continues to deliver tangible results by supporting officials working on real audit and investigation cases.
A central theme of this year's report is the evolution of TIWB into a more collaborative and regionally driven model of capacity building. Through the new TIWB Graduates Platform, jurisdictions that have successfully completed TIWB programmes are now sharing their expertise with peers facing similar challenges. Colombia, Egypt, the Maldives and Zambia are among the administrations now providing support to other developing countries, demonstrating how recipient jurisdictions can become providers of technical assistance and helping create a more sustainable cycle of knowledge sharing.
"Mobilising domestic resources is one of the most powerful ways for countries to achieve their growth and development goals," OECD Secretary-General Mathias Cormann said. "Tax Inspectors Without Borders shows that practical, peer-to-peer support can deliver remarkable results, strengthening tax systems, building lasting capacity, and delivering billions in additional public revenues."
The annual report highlights the rollout of TIWB 2.0, an enhanced framework designed to respond to growing demand and an increasingly complex international tax environment. Building on the initiative's proven model, the next phase will deliver more effective, sustainable, and regionally-anchored assistance. It also places its focus on broadening support into specialised areas such as industry-specific audits, criminal tax investigations and the effective use of automatic exchange of information and country-by-country reporting data.
The new approach is already delivering results. In 2026, Botswana became the first jurisdiction to receive tourism-sector tax expertise from the Maldives through a TIWB programme, demonstrating how knowledge developed in one developing country can be successfully shared with another facing similar challenges.
"Domestic resource mobilisation is one of the most powerful tools countries have to finance their own development and strengthen economic resilience," said UNDP Administrator Alexander De Croo. "The success of Tax Inspectors Without Borders demonstrates what can be achieved when international expertise, national ownership and long-term partnerships come together to build stronger institutions. By strengthening tax systems, countries are not only increasing revenues today - they are expanding the fiscal space needed to invest in sustainable development, resilience and long-term prosperity."
TIWB's work underscores the importance of effective and transparent tax systems in enabling countries to finance public services, reduce poverty and support long-term growth, while responding to an evolving international tax environment shaped by digitalisation, complex cross-border transactions and illicit financial flows.
The findings of the annual report will be discussed at the 2026 TIWB Governing Board meeting, which brings together Commissioners of participating tax administrations, representatives from donor countries and members of civil society, to review TIWB's strategic direction and provide guidance to strengthen the scale and impact of the initiative.
TIWB's impact continues to be underpinned by a growing network of 32 partner administrations, alongside regional organisations and donors. Strong partnerships, particularly in Africa through collaboration with the African Tax Administration Forum (ATAF), have helped strengthen regional expertise and support countries in addressing increasingly complex tax challenges.
