Consumption responses to sweetened beverage taxes by household income in four U.S. cities

Taxes on sweetened beverages have become an important policy response to growing obesity rates and the prevalence of type 2 diabetes in the U.S. and other nations. Since 2015, eight U.S. cities have implemented these taxes, but so far direct evidence of their impacts on household purchasing behavior is scarce. Of particular interest to many researchers and policy makers is the response of lower-income consumers to these taxes, both because they have higher sweetened beverage consumption on average and because of concerns that sweetened beverage taxes are regressive. This project investigates the income-stratified household response to SSB taxes using a data set containing the purchasing behavior of approximately 400 households in the cities of Seattle, San Francisco, Oakland, and Philadelphia, all of which have recently introduced beverage taxes. Using doubly-robust estimation of dynamic and heterogeneous treatment effects relative to a propensity-matched set of households in three comparison cities, we find that households in taxed cities experience increased prices and reduce their purchases of those beverages, with no evidence of cross-border shopping. We further find differential tax impacts by income level, with lower-income households (households with income <200% of the federal poverty line for their size) reducing their purchases of taxed beverages by nearly 50% - more than double the 18% reduction found in higher-income households (households with income >400% of the federal poverty line for their size). Our finding that lower-income households decrease their consumption more than twice as much as higher-income households suggests that these taxes may reduce health disparities and promote population health.