New analysis by departmental researchers suggests the government has missed a key opportunity to maximise the health benefits of the UK soft drinks tax, particularly as latest NHS data shows childhood obesity inequalities are widening rather than narrowing.
The analysis, published in The BMJ today, finds that introducing a higher tax rate for drinks containing 10g or more sugar per 100ml could remove twice as much sugar from the market compared to the government's current proposals.
The research, led by Dr Lauren Bandy and Professor Peter Scarborough, comes as recent NHS data shows that children from the most deprived areas are now twice as likely to be obese as those from the least deprived areas – a gap that has widened since 2009.
Critical timing as budget decision looms
The analysis arrives as the government prepares to announce final decisions on the Soft Drinks Industry Levy (SDIL) at the Autumn Budget 2025, following a review and public consultation that closed in July.
The SDIL currently taxes drinks at different rates depending on sugar content, with the highest rate applying to drinks over 8g per 100ml. While the government is proposing to lower the tax threshold from 5g to 4g of sugar per 100ml and extend the tax to include sweetened milk drinks, earlier plans for a higher tax rate on the most sugary products have been dropped. The consultation document notes this decision followed "discussions with stakeholders."
Dr Bandy said: "With 30% of Year 6 children in England's most deprived areas now living with obesity – double the rate compared to affluent areas – we need policies that target the biggest sources of excess sugar. The proposed changes will capture more products, but many of these brands already reformulated when the tax was first introduced. Meanwhile, the highest-sugar drinks remain unchallenged."
The biggest impact would come from targeting high-sugar drinks
The researchers' analysis reveals that if manufacturers reformulated products to avoid a new higher tax rate on drinks over 10g per 100ml, this would remove twice as much sugar from the market as lowering the threshold to 4g per 100ml.
The three top-selling high-sugar brands – Red Bull, Coca-Cola and Monster Energy – contain between 10.5 and 11g of sugar per 100ml and did not reformulate when the SDIL was introduced in 2018. Some contain more than double a child's daily recommended sugar intake in a single serving.
Together, these three brands sold 935 million litres in the UK in 2024. In comparison, the three top-selling brands that would be newly captured by lowering the threshold to 4g – Fanta, Irn Bru and Pepsi – sold 502 million litres. All three of these brands already reformulated to reduce sugar when the SDIL was first introduced.
Professor Scarborough added: "Our analysis suggests that targeting very high-sugar drinks could remove twice as much sugar from the market as the current proposals. Given the government's ambition for children to be the 'healthiest generation ever', this represents a significant missed opportunity."
Building on a proven public health success
The SDIL has been recognised as a public health success since its introduction, with studies showing it has achieved a 46% average reduction in sugar content in targeted drinks, decreased consumption of sugary drinks, and is associated with reductions in childhood obesity and tooth decay.
Research shows the policy has had larger positive impacts on more deprived groups – exactly where the most serious problems now exist, with NHS data showing obesity levels of over 30% among Year 6 children in the most deprived areas.
With UK children's sugar intake more than double the recommended maximum and hospital treatments for obesity increasing fourfold over the past decade, the researchers argue that targeting the highest-sugar products should be a priority.
The study analysed data from major UK supermarkets and sales figures from across the market. It found that lowering the tax threshold to 4g per 100ml would affect 814 products currently on the market, while a new higher rate for products over 10g per 100ml would target 298 products – including the market's biggest sellers.
Dr Bandy concluded: "The SDIL is a flagship policy that has already demonstrated real health benefits, particularly for children from disadvantaged backgrounds. Our analysis shows there's still an opportunity to strengthen its impact by focusing on the products with the highest sugar content."
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Read the analysis here:
Bandy L, Scarborough P. Changes to UK soft drinks tax are a missed opportunity for public health BMJ 2025; 391 :e086062 doi:10.1136/bmj-2025-086062