The nutritional and welfare effects of threshold sin taxes: evidence from the UK sugar tax
14 Oct 2026
15:00 -16:00
Times shown in local time
Open to: All
Castle Teaching Room (Cambridge Judge Business School)
Trumpington St
Cambridge
CB2 1AG
United Kingdom
Join our upcoming Economics and Policy seminar
Speaker: Professor Stephan Seiler, Imperial College London
About the seminar topic
We study the UK sugar tax, which only applies to beverages with sugar content above a threshold and triggered widespread reformulation. We estimate a structural model of beverage demand and firms’ price setting using household-level data from before and after the tax. We find that the tax reduced sugar consumption from beverages by 47%. Monetised health gains (from externalities and internalities) outweigh the consumer welfare loss, leading to an increase in total welfare. Reformulation accounts for 29% of the sugar reduction at almost no cost to consumers, although it halves tax revenue. Matching the UK’s sugar reduction with a volumetric tax requires nearly double its rate and imposes a much greater consumer welfare loss. Broadening the tax base to diet beverages leads to less sugar reduction and a higher consumer welfare loss. Both alternatives raise more tax revenue, but neither matches the threshold tax’s total welfare gain.
Speaker bio
Stephan Seiler is a Professor of Marketing and Economics (by courtesy) at Imperial College London. He received his PhD from the London School of Economics and was previously employed at Stanford and UCLA. Professor Seiler was named a Marketing Science Institute ‘Young Scholar’ as well as subsequently an MSI ‘Scholar’ and has won several best paper awards in marketing and economics. He was awarded the Faculty Excellence Award for teaching in the Master of Science in Business Analytics programme at UCLA in 2020, the Marketing Science Service Award for his work as Associate Editor at the journal in 2024, and the Imperial Business School Teaching Excellence award for PhD supervision in 2024/25. He is currently a co-editor at Quantitative Marketing and Economics and an associate editor at Management Science, the Journal of Marketing Research, and the Journal of Industrial Economics. He co-organises the European Quant Marketing Seminar series.
His research focuses on consumer choice in various markets. He analyses issues ranging from the choice of hospital for a bypass operation to the reaction of consumers to promotions of laundry detergent. He is particularly interested in understanding consumer search behaviour, such as how informed consumers are about prices or other product characteristics when making a purchase decision. Another strand of his research analyses the production and impact of user-generated content on platforms such as Wikipedia and Twitter.
Register
No registration required. If you have any questions about this seminar, please email Emily Brown.