市民循環拠出 (Ccc): 消費課税の逆進性に対する構造的緩和装置と市民間水平的相互扶助循環[Citizen Circulation Contribution (CCC): A Structural Mechanism for Mitigating the Regressivity of Consumption Taxation and a Horizontal Mutual-Aid Circulation among Citizens]

This paper proposes the Citizen Circulation Contribution (CCC) as a structural mechanism for mitigating the regressivity of consumption taxation. CCC is a mechanism in which a fixed-rate contribution is collected at the time of payment for transactions subject to consumption tax, accumulated in the CCC Pool (Citizen Circulation Contribution Pool) without being incorporated into the state's general revenue, and distributed monthly in equal amounts to all public health insurance enrollees and recipients of medical assistance. Through the asymmetric structure of "uniform-rate collection and equal-amount distribution," households with lower consumption are expected to receive larger net benefits, in the sense that the amount received exceeds the amount contributed, thereby structurally mitigating the regressivity of consumption taxation. This paper presents CCC not only as a tax-design mechanism, but also through a two-layer structural framework that understands it as a horizontal mutual-aid circulation among citizens. The first-layer function—mitigating the regressivity of consumption taxation—and the second-layer structural character—mutual-aid circulation—are logically independent. The institutional distinctiveness of CCC lies in the fact that the second layer can function on its own in the form of manual operation (M-CCC) when digital infrastructure becomes inoperative. In the simulation, assuming household final consumption expenditure of 351 trillion yen, of which approximately 75 percent, or about 263 trillion yen, is subject to consumption tax, and a population of approximately 123 million, a contribution rate of 2.5 percent yields a monthly per-capita distribution of approximately 4,450 yen, while a rate of 15 percent yields approximately 26,700 yen. Through comparisons with refundable tax credits, resident tax credits with social insurance premium refunds, and consumption tax increase plus universal cash benefit schemes, this paper argues that CCC occupies a structurally distinct position from existing systems along the axes of fund ownership, political reversibility, institutional meaning, basis of eligibility, and source of legitimacy. The scope of this paper is limited to CCC as a mitigation device within tax design; implementation issues, including constitutionality, are left for separate specialized examination.