Paper Publication Overview
The Policy Research Institute, Ministry of Finance, published Discussion Paper No. 381 "Estimation of Top Income Shares in Japan Using Income Tax Data: 2008-2023" in September 2025. This paper presents the latest research results analyzing the reality of income inequality in detail.
Research Authors and Structure
Main authors:
- Visiting Researcher, Policy Research Institute, Ministry of Finance: Tomohiro Iguchi
- Deputy Director, Policy Research Institute, Ministry of Finance: Junji Ueda
- Former Researcher, Policy Research Institute, Ministry of Finance: Akinobu Sato
- Senior Visiting Researcher, Policy Research Institute, Ministry of Finance / Professor, Institute of Economic Research, Hitotsubashi University: Chiaki Moriguchi
Research Methodology and Data Characteristics
Analysis period: 2008-2023 (16-year longitudinal survey) Data used: Income tax return data (utilizing actual tax administration data) Research keywords: Top income shares, income distribution, capital gains income, wage income distribution Academic classification: JEL codes D31 (Personal Income, Wealth, and Their Distributions), H24 (Taxation, Subsidies, Personal Income Taxation), J31 (Wage Level and Structure), N35 (Labor and Consumers, Demography)
Academic and Policy Significance of Analysis
Contribution to inequality research: Precise understanding of top income earners' reality through tax administration data Policy planning support: Utilized as basic material for income distribution policy and tax system reform International comparability: Enables comparative analysis with similar research conducted in countries worldwide Economic trend understanding: Tracking income inequality changes under long-term economic fluctuations from post-Lehman Shock through COVID-19 pandemic
This research provides important academic foundations for elucidating Japan's income inequality reality and policy planning.