It is generally difficult to measure revenue not collected due to noncompliance, but a growing number of countries now regularly produce and publish estimated revenue losses. Good tax gap analysis enables the detection of changes in taxpayer behavior by consistent estimates over time. This Technical Note sets out the theoretical concepts for personal income tax (PIT) gap estimation, the different measurement approaches available, and their implications for the scope and presentation of statistics. The note also focuses on the practical steps for measuring the PIT gap by establishing a random audit program to collect data, and how to scale findings from the sample to the population.

Experts discuss strategies for curtailing tax evasion

Building on previous FAD work in the tax administration field, this paper defines broad criteria for diagnosing the problems in a country’s tax administration and formulating an appropriate reform strategy. To be effective, this strategy should be based on the size of the tax gap and the country’s particular circumstances. This paper discusses some guiding principles which have provided the basis for successful reforms, including: reducing the tax system’s complexity, encouraging taxpayers’ voluntary compliance, differentiating the treatment of taxpayers by their revenue potential, and ensuring the reform’s effective management. Also discussed are specific bottlenecks that hinder the effectiveness of the tax administration’s operations.

People pay taxes for two reasons. On the positive side, most people recognize, even if grudgingly, that payment of tax is a duty of citizenship. On the negative side, they know that the law requires payment, that evasion is a crime, and that willful failure to pay taxes is punishable by fines or imprisonment. The practical questions for tax administration are how to strengthen each of these motives to comply with the law. How much should be spent on enforcement and how should enforcement be organized to promote these objectives and achieve the best results per dollar spent? Over the last few years, the U.S. Congress has restricted spending on tax administration, forcing the Internal Revenue Service to curtail enforcement activities, at the same time, that the number of individual filers has increased, tax rules have become more complex, and more business have become multinational operations. But if too many cases of tax evasion go undetected and unpunished, those who may have grudgingly paid their taxes may soon find it easier to join the scofflaws. These events in combination have created a genuine crisis in tax administration. The chapters in this volume evaluate the capacity of authorities to enforce the tax laws in a modern, global economy and examine the implications of failing to do so. Specific aspects of tax law, including tax shelters, issues relating to small businesses, tax software, role of tax preparers, and the objectives of tax simplification are examined in detail. The volume also builds a conceptual basis for future scholarship, with regard not only to tax administration, but also to such fundamental questions as whether taxpayers respond mostly to economic incentives or are influenced by their experiences with the filing process and what is the proper framework for evaluating the allocation of resources within the IRS.

This report is the ninth edition of the OECD's Tax Administration Series. It provides internationally comparative data on aspects of tax systems and their administration in 59 advanced and emerging economies.