On January 1, 2018, the United Kingdom introduced a tax on sweetened beverages, two tiers, 18p per liter for drinks with 5-8g of sugar per 100ml, and 24p per liter for drinks with more than 8g per 100ml. Drinks with at least 75% juice and milk-based drinks were exempt.

By the time the tax took effect, it had already achieved a significant portion of its goal. Manufacturers reformulated 50% of taxed beverages in advance of the law to avoid the tax tier, reducing sugar content in the drinks themselves rather than passing costs to consumers. The Lucozade Energy drink went from 8.9g to 4.5g of sugar per 100ml. Ribena dropped from 10g to 4.9g. The UK’s sugar intake from taxed beverages fell before anyone paid a penny of tax.

How Sugar Taxes Work

Sugar taxes on beverages typically take one of three forms:

Volume-based: A flat tax per unit of volume, regardless of sugar content. Mexico’s tax of 1 peso per liter is this type. Simple to administer, doesn’t incentivize reformulation.

Tiered by sugar content: Tax rate increases above a sugar threshold. The UK model. Creates direct incentive for manufacturers to reformulate below the threshold.

Ad valorem: A percentage of the product’s price. Less common for sugar taxes specifically.

Most implemented taxes target sweetened beverages specifically, not sugar as a food ingredient broadly, because beverages are administratively simple to tax (defined product category, easy to measure sugar content) and because the public health case against liquid calories is particularly strong.

Where Sugar Taxes Have Been Implemented

Mexico was the first major country: a 10% tax on sweetened beverages starting in 2014. Berkeley, California was the first US city: 1 cent per ounce starting 2015. Philadelphia, Seattle, Boulder, San Francisco, Chicago (briefly, then repealed), and several other US cities followed. France has had a tiered sugar tax since 2012. The UK in 2018. Chile, South Africa, and Ireland in subsequent years.

As of 2024, more than 50 countries and numerous cities have implemented some form of sweetened beverage tax.

What the Evidence Shows

Mexico: A 2017 study in PLOS Medicine found that sweetened beverage purchases fell by 7.6% in the first year and 9.7% in the second year following the tax. Water purchases increased by 13.1% in the first year. Lower-income households showed the largest reductions.

Berkeley: A 2016 study in PLOS Medicine found a 21% decrease in consumption of sugary beverages in low-income neighborhoods one year after the tax, with a 63% increase in water consumption. Effect sizes in Berkeley were larger than in Mexico, partly because the Berkeley tax was proportionally larger.

UK: A 2023 study in PLOS Medicine found the UK soft drinks industry levy was associated with a 6.4% reduction in sugar from retailer soft drinks. Critically, nearly all the reduction came from reformulation, not reduced consumption.

Philadelphia: Results were more mixed. A study found significant sales declines in Philadelphia, but a substantial portion of that was offset by increased purchases in surrounding counties — consumers who drove outside the city to buy untaxed beverages. This “border leakage” effect is a persistent challenge for city-level taxes that don’t apply statewide.

The Arguments For

Health effectiveness: Even modest reductions in sugary beverage consumption in populations that drink large amounts have meaningful effects at scale. A 10% reduction across Mexico’s 130 million people represents an enormous absolute reduction in sugar consumption.

Reformulation incentive: The UK case showed that tiered taxes can achieve most of their public health benefit through industry reformulation rather than consumption reduction. Manufacturers change their products rather than lose market share. This doesn’t require individual behavior change at all.

Revenue for public health: Taxes generate revenue that can be directed to health programs. Philadelphia directed some of its beverage tax revenue to pre-K education, though not specifically to health programs, illustrating both the fiscal benefit and the political complexity of earmarking.

Equity: Sweetened beverage consumption is highest in lower-income and minority communities, who also bear disproportionate burdens of obesity and type 2 diabetes. Taxes that reduce this consumption could reduce health disparities.

The Arguments Against

Regressive taxation: Taxes that represent a larger share of income for poorer consumers, which percentage taxes on food and drink typically do, are regressive. A beverage tax costs a lower-income family a higher fraction of their income than a wealthy family buying the same product.

Limited scope: Beverages are a large but not exclusive source of added sugar. A beverage tax that doesn’t cover candy, desserts, or packaged food with added sugar addresses one component of the problem while leaving others untouched.

Industry response: Manufacturers reformulate products in ways that sometimes replace sugar with other ingredients, artificial sweeteners, sodium, that carry their own contested health profiles.

Efficacy questions: Border effects in small jurisdictions limit real-world effectiveness. The question of whether consumption reductions translate to health outcomes (not just purchase data) is hard to measure within the timeframes most studies use.

Individual liberty: The most principled opposition argues that taxing legal food products to influence behavior is paternalistic, and that the role of government in managing diet is appropriately limited to information provision, not price manipulation.

The Evidence Summary

The research consistently shows that sugar taxes reduce purchases of taxed products and, in tiered systems, drive reformulation. The reductions are real but modest, typically in the 6-21% range for purchases. Whether purchase reductions translate to meaningful improvements in population health outcomes like obesity or diabetes rates over a 5-10 year timeframe is harder to establish, and no jurisdiction has yet demonstrated this at the population level.

That gap (proven behavior change, unproven health outcomes) is where most of the serious policy debate sits.

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