Structural Opacity in the Allocation of Japan's Consumption Tax to Social Security Finance: A Primary-Source-Based Institutional Analysis

This study provides a comprehensive institutional analysis of how Japan’s consumption tax is allocated to social security finance, relying exclusively on verifiable primary sources such as statutory texts, budget documents, official statistics, audit reports, administrative evaluation reports, and Diet transcripts. The paper reconstructs the fiscal architecture linking consumption tax revenue to social security expenditure across both the general account and multiple special accounts, highlighting the structural features that limit the traceability of revenue–expenditure relationships. The analysis incorporates internationally recognised fiscal transparency standards, including the OECD Best Practices for Budget Transparency and the IMF Fiscal Transparency Code, to situate Japan’s fiscal system in a comparative context. The study demonstrates that the breadth of the “social security” category, the dual-account structure of Japan’s public finance, and persistent weaknesses in performance evaluation collectively generate a condition of structural opacity. This opacity does not imply misconduct but reflects institutional configurations that prevent itemised identification of how consumption tax revenue supports specific social security programmes. By grounding the discussion entirely in official documents, the paper offers a reproducible and evidence-based contribution to research on fiscal transparency, public finance, and social policy governance. It also provides a methodological model for analysing earmarked or quasi-earmarked taxes in other national contexts.