Using supermarket loyalty card data to measure the differential impact of the UK soft drink sugar tax on buyer behaviour

This paper explores the impact of the soft drinks sugar tax introduced in the UK in 2018 on the purchasing behaviours of different geo‐demographic consumer segments. We analyse data for a composite good comprising the most popular sugar‐sweetened drinks (SSDs) using loyalty card data from one of the UK’s largest supermarkets. We use pre‐levy data to predict the effect of the tax and corroborate our predictions by analysing actual consumption of the composite good in the first 5 months post‐levy. The results show that the impact of the sugar tax is likely to have the desired effect of reducing the purchase of SSDs. Moreover, though the impact of the tax is likely to vary across different geo‐demographic segments, the evidence suggests that its impact is likely to be greatest on the most vulnerable market segments – families on low incomes – who are among the highest consumers of SSDs in the UK.