税收横向公平：公民信仰与政策偏好

Horizontal Equity of Taxation Citizen Beliefs and Policy Preferences Pierre BachasChristopher HoyAnders JensenMahvish Shaukat Fiscal Policy and Growth Global DepartmentApril 2026 A verified reproducibility package for this paper isavailable athttp://reproducibility.worldbank.org,clickherefor direct access. Policy Research Working Paper11367 Abstract Horizontal inequity occurs when employees and self-em-ployed workers with the same income end up with differenteffective tax burdens, due to the difficulty of enforcing taxeson the self-employed. Based on detailed micro-tax sim-ulation models integrated with household surveys in 25developing countries, this paper shows that tax systemsincur large horizontal inequities in practice, and reforms that improve vertical equity worsen horizontal equityby a comparable amount. In-person and online surveysacross multiple countries reveal widespread concern abouthorizontal equity. Randomized information treatmentsheighten this concern but do not shift tax preferencestoward addressing horizontal inequity. The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about developmentissues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry thenames of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely thoseof the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank andits affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent. Horizontal Equity of Taxation:Citizen Beliefs and Policy Preferences∗ Pierre Bachas†World BankChristopher Hoy‡World BankAnders Jensen§HKS & NBERMahvish Shaukat¶World Bank JELCodes:D63,D72,H22,H24,H26,C93Keywords:Horizontalinequity,verticalequity,personalincometax,citizenbeliefs 1Introduction Tax inequity hinders tax collection and weakens the fiscal contract between citizens andthe state.Historically, taxes perceived as arbitrary or unfair have contributed to politicalinstability, protests, and revolts in contexts as varied as early modern France (Davoine et al.,2025), colonial Nigeria (Afolabi, 2022), and the mid-20th-century Soviet Union (Keen andSlemrod, 2021). A well-known recent example is Warren Buffett’s observation that he faceda lower tax rate than his secretary.While anecdotal, it reflects a pervasive feature of taxsystems: income that is closely held and controlled by its owners—subject to limited third-party reporting and greater tax planning opportunities often faces lower effective taxationthan wages.This disparity spans the income distribution, from self-employed individualswho can underreport income or deduct personal consumption as business expenses (Leite,2024), to large firm owners who structure income to minimize or defer taxes and achieveeffective tax rates below the population average (Bach et al., 2023; Bruil et al., 2025). Taxing closely held income poses a challenge globally, driven less by preferential treat-ment and lax enforcement than by structural difficulties in curbing evasion for this typeof income.Studies from around the world consistently show that 50 to 70 percent of in-come from self-employment goes undeclared in income taxes; in contrast, the evasion ratefor salaried employees is typically below 10 percent, owing to third-party reporting andemployer withholding. As a result, two individuals with identical earned incomes - one self-employed and one salaried - might pay very different amounts in taxes, generating a starkcase of horizontal inequity. While the challenge is general, the problem is acute in developingcountries where the self-employed constitute a large share of the labor force, including in thetop decile where they represent almost half of all workers (Jensen, 2022). Accordingly, horizontal inequity in income taxation is a salient concern for policy makers,as underscored by the Indian Finance Minister in 2018: "Income tax data analysis suggests that a major portion of personal income-taxcollection comes from the salaried class. Perceptions of fairness suffer when theemployee class is forced to contribute disproportionately to income taxes while theclass of self-employed gets away with paying minimal taxes." How large is tax inequity between self-employed workers and employees in practice? Howdo citizens perceive this disparity? This paper makes two contributions. First, we build taxsimulation models for a set of developing countries to quantify horizontal inequities arisingfrom differences in employment structure and tax evasion.We document large horizontaldisparities: a self-employed worker in the top income decile pays 6 percentage points lessin taxes than an otherwise comparable employee (36% less in relative terms).This gap is compa