The Taxation of Concealed Offshore Wealth: Evidence from US Enforcement and Implications for Inequality

在美国、英国和一些欧洲国家，收入和财富不平等正在加剧。对日益加剧的不平等的担忧，重新引发了公众对利用累进税收政策来遏制不平等的兴趣。然而，在实践中，一个关键因素限制了现代政府对高收入、高财富个人征税的能力：利用离岸财富逃税。我们现有的证据表明，处于收入和财富分配顶端的个人所赚取的收入和财富中，有很大一部分流入了隐蔽的离岸账户，这些账户通常是免税的。该项目研究了利用离岸财富逃税所造成的两个严重问题。第一个问题是直接的政策挑战：鉴于难以察觉，各国如何对来自离岸财富的收入征税？第二个问题是一个涉及下游政策后果的学术问题：在收入分配的顶端有多少逃税行为，这对我们衡量不平等的标准有何影响？本研究项目将使用美国国税局（IRS）的行政数据来回答这两个问题。美国是研究这些问题的理想环境，因为它是一个富裕的国家，而且美国最近实施了针对离岸财富的越来越激进的政策。从2009年开始，美国几乎动用了所有可用的工具，包括诉讼、基于举报人数据的起诉，最重要的是，通过了新的立法。2012年开始实施的《外国账户税收合规法案》（Foreign Accounts Tax Compliance Act）现在要求美国以外的金融机构向美国当局报告在这些机构持有的美国人财富及其相关收入。研究这些政策的影响将有助于我们了解针对离岸财富的税收执法是否有效，而通过政策实施产生的数据可以为离岸财富对衡量不平等的重要性提供无与伦比的见解。该项目的第一部分是使用数据来检查执法对逃税的影响。我们从非常简单的汇总数据分析开始，展示离岸财富和收入的报告是如何随着时间的推移而演变的。初步结果表明，执法对报告产生了极其强烈的影响，这在简单的汇总数据中是可见的。然后，我们将使用因果微观计量经济学研究设计来了解汇总数据中的模式是否归因于执行，并在几个维度上估计政策的总体影响。我们将根据财富的位置、所有者在收入分配中的排名以及持有资产的方式（直接持有或通过空壳公司持有）来估计执法的总体影响。总之，这应该提供改革影响的详细概述，这是对这些执行政策正在进行的有争议的辩论的重要投入。第二部分问，我们可以从离岸财富的新数据中了解到什么关于逃税和不平等的信息。大多数衡量不平等的指标，比如前1%的收入份额，都是用个人所得税申报表的数据来估计的。如果人们通过隐藏财富来逃避所得税，一些收入就不会出现在纳税申报单上，从而使对最高收入份额的估计产生偏差。与此同时，通常用于研究逃税程度的随机审计，实际上从未发现隐藏的离岸财富。我们将把有关美国离岸逃税的广泛数据与对随机抽样的个人进行审计时逃税的传统数据结合起来。我们将估计整个收入和财富分配中的逃税程度，并估计排除离岸逃税的最高收入和财富份额。这种分布统计对于关于不平等的辩论至关重要。

Income and wealth inequality are on the rise in the US, the UK and some European countries. Concerns over growing inequality have led to renewed public interest in the use of progressive tax policy to curtail it. In practice, however, one key factor limits the ability of modern governments from taxing very high-income, high-wealth individuals: the use of offshore wealth to evade taxes. What evidence we have suggests that a significant share of the income and wealth earned by individuals at the top of the income and wealth distributions accrues to concealed offshore accounts, where it generally goes untaxed.This project studies two serious problems created by the use of offshore wealth to evade tax. The first problem is a direct policy challenge: how can countries tax income derived from offshore wealth, given that it is difficult to detect? The second problem is an academic problem with downstream policy consequences: just how much tax evasion is there at the top of the distribution, and how does this affect our measures of inequality?This research project will answer these two questions using administrative data from the United States Internal Revenue Service (IRS). The US is the ideal setting to study these questions because it is a wealthy country, and because the US recently implemented increasingly aggressive policies targeting offshore wealth. Starting in 2009, the US used virtually every tool at its disposal, including lawsuits, prosecutions based on data from whistleblowers, and, most importantly, the passage of new legislation. The Foreign Accounts Tax Compliance Act, implemented starting in 2012, now requires that financial institutions outside the US report to US authorities on Americans' wealth held at those institutions and the associated income. Examining the impact of these policies will help us understand whether tax enforcement targeting offshore wealth can be effective, and the data generated via the implementation of the policies can provide unparalleled insights on the importance of offshore wealth for the measurement of inequality.The first part of the project is to use data to examine the impact of enforcement on tax evasion. We begin with very simple aggregate data analysis, showing how the reporting of offshore wealth and income has evolved over time. Preliminary results suggest that enforcement had an extremely strong effect on reporting, which is visible in simple aggregate data. We will then use causal microeconometric research designs to understand whether patterns in aggregate data are attributable to enforcement, and to estimate the total impact of the policy along several dimensions. We will estimate how the overall impact of enforcement varies by the location of wealth, by owners' rank in the income distribution, and by the method of holding of assets - directly or through shell corporations. Together, this should provide a detailed overview of the impact of the reform, which is an important input into the ongoing and controversial debate over these enforcement policies.The second part asks what we can learn about tax evasion and inequality from new data on offshore wealth. Most measures of inequality, such as top 1% income shares, are estimated using data from individual income tax returns. If people evade income taxes by concealing their wealth, some income never appears on tax returns, biasing estimates of top income shares. Simultaneously, the random audits conventionally used for research on the extent of evasion virtually never detect concealed offshore wealth. We will combine a wide array data on offshore tax evasion in the US with conventional data on evasion from audits of a random sample of individuals. We will estimate the extent of evasion throughout the income and wealth distributions, and estimate top income and wealth shares that correct for offshore evasion. Such distributional statistics are vitally important for the debate over inequality.