Abstract
Background: Many jurisdictions have implemented taxes on sugar-sweetened beverages (SSBs) as an upstream approach to disease prevention. The aim of this dissertation was to conduct a systematic review on the range of SSB tax 'pass-through' rates, or the rate at which SSB taxes translate to an increased cost to consumers. Pass-through rates are important because research has shown that the higher the price for consumers, the more effective a taxation policy is at producing behaviour change and positively impacting population health.
Methods: A systematic search of the literature was conducted in the databases Scopus, PubMed, EconLit, and Google Scholar for articles published between January 2000 and July 2019. Peer- reviewed English-language articles were included if they reported original price data from real- world SSB tax interventions. Information regarding the tax policy design, the study design and methods, as well as the pass-through rates based on beverage type, brand, retailer type, package size, and other reported variables were extracted and synthesized.
Results: A total of 14 studies with 15 study designs from seven jurisdictions, Mexico (n=3), Berkeley (n=3), Philadelphia (n=3), Chile (n=2), Barbados (n=1), France (n=1), and South Africa (n=1), were included in the final review. The type of taxes ranged from volumetric, sugar- based, and ad valorem. The datasets used in the analyses included privately-owned datasets (n=6), government-owned datasets (n=4), and hand-collected datasets (n=5). A total of 136 pass-through rates were obtained or calculated. There was evidence of both undershifting and overshifting, but the majority of beverages experienced undershifting with a median value of 67% for SSBs overall. Variations in the reported pass-through rate were found both within and across jurisdictions, and varied based on characteristics such as, beverage type, brand, retailer type, package size, and other reported variables. The tax policy design as well as the study design methods were shown to influence the reported pass-through rates.
Conclusions: The results from this systematic review provide strong evidence that SSB prices increase in response to the enactment of SSB taxes, but that they undershift and do not result in the full tax price increase for consumers. If policymakers wish to maximise the impact of SSB taxes they may need to consider higher taxes and supplementary interventions, such as minimum prices on SSBs.