Who Pays for Payments?

We use novel data on the composition and cost of payments across U.S. merchants to quantify consumer redistribution in the payment system. Cards charge interchange fees to merchants to fund consumer rewards. When merchants raise prices for all consumers in response to these costs, users of low-cost payment methods (e.g., cash and debit) cross-subsidize high-reward credit card users who shop at the same merchant. This standard mechanism implicitly assumes that consumers using different payment methods shop at the same merchants and that merchants face similar fees. We show instead that incidence depends on the joint distribution of payment choices across merchants. We document two key forces that shape redistribution. First, consumer sorting--where consumers who use different payment methods shop at different merchants--limits the exposure of cash and debit users to the effects of high interchange fees. Second, interchange fees vary across merchants; where users of different payment methods overlap, such as at large grocery stores, fees are lower due to sector discounts and private negotiations. We embed these forces in a sufficient-statistics framework that maps observed heterogeneity directly into redistribution. We estimate that interchange fees transfer approximately $30 billion every year from cash and debit users to credit card users. Consumer sorting and merchant fee heterogeneity reduce the magnitude of this regressive transfer by 25%, but do not eliminate it. Finally, we show that both the Durbin Amendment and the rise of premium credit cards have been regressive, highlighting how policy and innovation can reshape the incidence of platform fees