Horizontal inequity occurs when employees and self-employed with the same income end up with different effective tax burdens, due to the difficulty of enforcing taxes on self-employed. Based on detailed micro-tax simulations models integrated with household surveys in 25 developing countries, we show that tax systems incur large horizontal inequities in practice and that reforms which improve vertical equity worsen horizontal equity by a comparable amount. An in-person survey in Pakistan and online surveys across multiple countries reveal widespread concern about horizontal equity. Randomized information treatments heighten this concern but do not shift tax preferences toward addressing horizontal inequity.
| Repository name | URI |
|---|---|
| Reproducible Research Repository (World Bank) | https://reproducibility.worldbank.org |
Paper exhibits were reproduced on a computer with the following specifications:
• OS: Windows 11 Enterprise
• Processor: Intel(R) Xeon(R) Gold 6226R CPU @ 2.90GHz
• Memory available: 32.0 GB
Runtime: ~2 hours.
To reproduce the findings in this paper, a replicator must:
Reproducibility_microsimulations/dofiles/0a_-master_horizontal_equity.do, and run it.Reproducibility_experiments/online survey/do/1_-master.do, and run it.Reproducibility_experiments/inperson survey/Dofile/1_master.do, and run it.Since some of the original data cannot be redistributed, the package includes the outputs produced by the authors, which can be used to review the results presented in the paper.
Some data is restricted and has not been included in the reproducibility package. For more details, please refer to the README file.
| Author | Affiliation | |
|---|---|---|
| Mahvish Shaukat | World Bank | mshaukat@worldbank.org |
| Pierre Bachas | World Bank | pbachas@worldbank.org |
| Anders Jensen | Harvard and NBER | anders_jensen@hks.harvard.edu |
| Christopher Hoy | World Bank and University of Melbourne | choy@worldbank.org |
2026-05-13
| Location | Code |
|---|---|
| World | WLD |
The materials in the reproducibility packages are distributed as they were prepared by the staff of the International Bank for Reconstruction and Development/The World Bank. The findings, interpretations, and conclusions expressed in this event do not necessarily reflect the views of the World Bank, the Executive Directors of the World Bank, or the governments they represent. The World Bank does not guarantee the accuracy of the materials included in the reproducibility package.
| Name | URI |
|---|---|
| MIT License | https://opensource.org/license/mit |
| World Bank IGO Rider | https://github.com/worldbank/metadata-editor/blob/main/WB-IGO-RIDER.md |
| Name | Affiliation | |
|---|---|---|
| Mahvish Shaukat | World Bank | mshaukat@worldbank.org |
| Reproducibility WBG | World Bank | reproducibility@worldbank.org |
| Name | Abbreviation | Affiliation | Role |
|---|---|---|---|
| Reproducibility WBG | DECDI | World Bank - Development Impact Department | Verification and preparation of metadata |
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