The need for additional revenue is substantial in many developing countries, but improving revenue mobilization has importance beyond that. Requirements for relieving poverty and improving infrastructure are substantial: achieving the Millennium Development Goals, for instance, may require low-income countries to raise their tax-GDP ratios by around 4 percentage points. But the quality of measures also matters: increasing revenue by further taxing readily compliant taxpayers can worsen distortions and perceived inequities conversely, reducing reliance on trade taxes can bring real structural gains that outweigh short-term revenue difficulties. More fundamentally still, the centrality of taxation in the exercise of state power means that more efficient, fairer, and less corrupt tax systems can spearhead improvement in wider governance relations.

There are emerging concerns and issues requiring greater attention. Challenges in international taxation and from regional integration are intensifying, and call for closer cooperation on tax matters - including with advanced economies - in both policy and administration, as well as further support for capacity building. Continued trade liberalization will put pressure on revenue in many lower-income countries. Scope to meet these and other revenue needs by simply raising standard VAT rates is becoming limited, so the potential lies largely in better improving compliance and scaling back preferential treatments. Not least, and important too for the wider legitimacy of tax systems, greater efforts can be made - requiring political will as much as technical capacity - in taxing elites and high-income/wealth individuals.