The impact of the Cook County, IL, Sweetened Beverage Tax on beverage prices

This study assessed the extent to which the Cook County, IL, Sweetened Beverage Tax (SBT) of one cent per ounce (oz) on sugar-sweetened and artificially sweetened beverages was passed on to consumers in the form of higher prices. We drew on universal product code-level store scanner data and used a pre-post intervention-comparison site difference-in-differences (DID) study design to estimate the impact of the Cook County SBT on prices of taxed beverages, across product categories and sizes, as well as on prices of untaxed beverages. The DID model results showed an over-shifting of the tax with a 119% pass-through rate, on average, across all taxed beverages in Cook County compared to its comparison site. This price change represented, on average, a 34% increase in prices of taxed beverages. For untaxed beverages, prices were estimated to increase slightly by 0.04 cents per oz driven mainly by an increase in milk prices (0.12 cents per oz). We also found some heterogeneity in tax pass-through for the taxed beverages by sweetened beverage product category and size with pass-through being higher, on average, for individual-size (126%) compared to family-size (117%) beverages and higher for energy drinks (145%) compared to other sweetened beverages. Based on the baseline prices of different categories and sizes of beverages, the effective percentage increase in beverage prices resulting from the Cook County SBT ranged from a 52% increase for family-size soda to a 10% increase for family-size energy drinks.