日時：1月8日（木）17:20-18:50
報告者：張 燁明  (上智大学)
場所：2号館11階経済学部会議室B
幹事：樋口 裕城
言語：日本語

タイトル：
Digital Taxation in Hybrid Platform Market
要旨：
I develop a model of digital taxation in a hybrid platform that operates both a reseller channel and a marketplace channel, and analyze its price and welfare effects. Digital services taxes emerged from concerns that multinational platforms could erode domestic corporate tax bases through profit shifting and headquarters relocation to low-tax jurisdictions, and they were implemented as market-based levies on revenues from digitally provided marketplace intermediation. I show that, in platform markets, such taxes can also increase total surplus by disciplining the platform’s marketplace take rate when it departs from the socially desirable level. The model delivers two main results. When the market is small or competition is mild, a tax on the take rate increases trade and expands production through reallocation toward the reseller channel. When the market is large, the optimal tax is interior and declines with competitive intensity: excessive taxation strengthens upstream bargaining power, worsens wholesale terms, and, via strategic complementarity in price competition, raises marketplace prices and contracts quantities. Overall, the analysis provides a framework for digital tax design that accommodates heterogeneity in market size and competitive conditions.