Our Work

Evaluation of the City of Seattle’s Sweetened Beverage Tax

In June 2017, the City of Seattle passed an Ordinance to impose a 1.75-cent-per-ounce tax on sugary beverages. The ordinance that created the Sweetened Beverage Tax also required the City to work with academic researchers to assess the impact of the tax (Ordinance 125324, Section 5B). We have proposed to evaluate the impact of this tax on economic outcomes, health behaviors and intermediate health outcomes. The evaluation shall also assess, but not be limited to, the process of implementing the tax. Finally, the Ordinance requires identification and assessment of food deserts in the city, and an evaluation of the effectiveness and efficiency of the foodbank network in the city. 

This five-year evaluation is a collaboration between Public Health – Seattle & King County, the University of Washington, Children’s Research Institute, and Fred Hutchinson Cancer Research Center

Our evaluation plan consists of 6 main components.

  • First, we will assess how prices of taxed and untaxed beverages change in response to the tax by collecting beverage prices before and after the tax in Seattle as well as in a comparison area.
  • Second, we will assess whether children’s dietary intake of sugary drinks changes in response to the tax by enrolling a cohort of children in Seattle and the comparison area, assessing baseline intake and then following them over time to see how sugar beverage intake changes. We will focus on low-income children and we will also use household food receipts to evaluate household spending on sugary drinks.
  • Third, we will interview key stakeholders to evaluated their perceptions and experience with the tax.
  • Fourth, we will conduct an analysis of the impact of the tax on jobs and revenue using administrative data from the state of Washington.
  • Fifth, we will evaluate the impact of the tax on children’s body mass index, using data from WIC records and from the Healthy Youth Survey.
  • Sixth, we will administer a norms and attitudes survey using a random digit dialing to get a representative sample of Seattle and to test how norms and attitudes change in association with the tax. 

The study team has published work so far from the retail audit, a survey of grocery, quick-service restaurants, and beverage shops, to understand beverage prices before and after the tax, the norms and attitudes survey, a survey of city residents assessing whether the SBT changes residents’ perceptions about sugary beverages and the tax itself, and the assessment of the availability of healthy food, limited healthy food availability areas in the City, and the City’s food bank network.