In previous studies on the social marginal cost of public funds (SMCF), the existing tax system has been assumed to be either arbitrary or optimal. This note explores another possibility: the existing tax system itself represents a political equilibrium. Our exploration proceeds in Meltzer and Richards (1981) political economy of redistributive taxation. An interesting feature of our finding is that the degree of income inequality as measured by the ratio of mean to median income can play an important role in estimating the SMCF and judging whether the level of redistribution is excessive or inadequate.

A unified treatment of the marginal cost of public funds, covering both its theoretical foundations and how the MCF concept can be used to analyze tax policy issues. The marginal cost of public funds (MCF) measures the loss incurred by society in raising additional revenues to finance government spending. The MCF has emerged as one of the most important concepts in public economics; it is a key component in evaluations of tax reforms, public expenditure programs, and other public policies. The Marginal Cost of Public Funds provides a unified treatment of the MCF, carefully developing its theoretical foundations in a variety of contexts and describing its application to a wide range of policies—from excise taxes in Thailand to public sector borrowing in Canada and the United States. The Marginal Cost of Public Funds develops the basic theory of the MCF within the framework of public economics and shows how it is related to the traditional measures of the efficiency loss from distortionary taxation. The MCF concept is then applied to the major sources of revenues for governments—sales and excise taxes, taxes on labor income, taxes on the return to capital, public sector borrowing, and intergovernmental grants. This book will be an essential reference for economists and public policy analysts both in and out of government. Exercises and recommendations for further reading at the end of each main chapter highlight its usefulness as a supplementary text in advanced undergraduate or graduate courses in public economics.

Recent estimates of the marginal cost of public funds differ substantially. Some studies argue that the efficiency cost of taxation counter the welfare gain connected to redistribution of income. Hence, the efficiency cost of taxation should not be included as a cost of public goods provision. Kleven and Kreiner (2006), however, argue that the cost of public goods provision may double in countries with a large welfare state due to exit from the labor market. This study shows that the cost of public goods provision should be increased with less than 15 percent when categorical transfers redistributed income even though taxation may lead to exit from the labor market.

There is a growing debate on the relative merits of universal and targeted social assistance transfers in achieving income redistribution objectives. While the benefits of targeting are clear, i.e., a larger poverty impact for a given transfer budget or lower fiscal cost for a given poverty impact, in practice targeting also comes with various costs, including incentive, administrative, social and political costs. The appropriate balance between targeted and universal transfers will therefore depend on how countries decide to trade-off these costs and benefits as well as on the potential for redistribution through taxes. This paper discusses the trade-offs that arise in different country contexts and the potential for strengthening fiscal redistribution in advanced and developing countries, including through expanding transfer coverage and progressive tax financing.

It is argued that taxation causes three kinds of deadweight losses and two types of direct costs. The deadweight losses arise from substitution, evasion, and avoidance activities while the direct costs are administrative and compliance costs. Some of these social costs tend to be discontinuous and/or nonconvex. Because most models of taxation ignore some components of the social costs of taxation, their conclusions cannot be of a general nature. An alternative approach to policy evaluation is to rely on a marginal efficiency cost of funds rule which can indicate appropriate directions of reforms. The paper discusses its merits, applicability, and limitations, as well as its relationship to other concepts.