We analyze the effects of various taxes on competing two-sided platforms. First, we consider nondiscriminating taxes. We show that specific taxes are entirely passed to the agents on the side on which they are levied; other agents and platforms are left unaffected. Transaction taxes hurt agents on both sides and benefit platforms. Ad valorem taxes are the only tax instrument that allows the tax authority to capture part of the platforms' profits. Second, regarding asymmetric taxes, we show that agents on the untaxed side benefit from the tax. At least one platform, possibly the taxed one, benefits from the tax.
INTRODUCTIONTwo-sided platforms intermediate between two distinct groups of economic agents that benefit from interacting with one another but fail to organize this interaction by their own forces because of high transaction costs. That is, the main function of two-sided platforms is to internalize the various external effects that the interaction between the two groups generate. Of particular interest are the cross-side effects that make the well-being of one group depend on the participation of the other group: in general, the more one group participates, the more valuable the platform becomes for the other group.Two-sided platforms are active in a large variety of settings, as exemplified by the following categories: hardware and software systems allow applications developers and end users to interact (e.g., Mac OS, Android, and PlayStation);transaction systems provide a method for payment to buyers and sellers that are willing to use it (e.g., Visa, Bitcoin, and PayPal); matchmakers help members of one group to find the right "match" within another group (e.g., Alibaba, Monster, and Meetic); exchanges help "buyers" and "sellers" search for feasible contracts and for the best prices (e.g., eBay, Booking.com, Wiley, and edX); crowdfunding platforms allow entrepreneurs to raise funds from a "crowd" of investors (e.g., Kickstarter, Indiegogo, and LendingClub); peer-to-peer marketplaces facilitate the exchange of goods and services between "peers" (e.g., Airbnb, Uber, EatWith, and TaskRabbit); digital media (including social networks and search engines)provide content to users and sell users' attention to advertisers (e.g., YouTube, Facebook, and Google Search).As the previous examples illustrate, a large number of platforms have developed (or created) their business through the Internet and the use of digital technologies. Some of these "digital platforms" have exploited the self-reinforcing nature of network effects, together with the global reach of the Internet, to become dominant players in many countries. One thinks, in particular, of the well-established "GAFAM" and the emerging "NATU." 1 These companies are well-known to generate very large profits but to pay, comparatively, very low effective corporate taxes. They are accused, especially in Europe, of "dodging" taxes by locating their activities and their profits in lower-taxed countries.Given the difficulty to tax the corporate income of global d...