Objective To determine whether there were changes in household purchases of drinks or confectionery one year after implementation of the UK Soft Drinks Industry Levy (SDIL). Design Controlled interrupted time series analysis. Participants Members of a commercial household purchasing panel (average weekly n=22183) resident in Great Britain, reporting from March 2014 – March 2019. Intervention a two tiered tax levied on manufacturers of soft drinks, announced in March 2016 and implemented in April 2018. Drinks with ≥8g sugar/100ml (high tier) are taxed at £0.24/litre, drinks with ≥5-<8g sugar/100ml (low tier) are taxed at £0.18/litre and drinks with <5g sugar/100ml (no levy) are not taxed. There are a number of exempt categories. Main outcome measures Absolute and relative differences in the volume of, and amount of sugar in, soft drinks categories, , all soft drinks combined, alcohol and confectionery, purchased per household per week one year after implementation compared to pre-announcement trends. Results In March 2019, compared to the counterfactual estimated from pre-announcement trends, purchased volume of drinks in the high levy tier reduced by 155ml (95% CI 240.5 to 69.5) per household per week or 44.3% (95% CI 59.9 to 28.7), with a corresponding fall in sugar purchased in these drinks of 18.0g (95% CI 32.3 to 3.6), or 45.9% (95% CI 68.8 to 22.9). Purchases of low tier drinks reduced by 177.3ml (95% CI 225.3 to 129.3) per household per week, or 85.9% (95% CI 95.1 to 76.7); with a 12.7g (95% CI 14.7 to 10.6) reduction in sugar in these drinks, equivalent to 88.3% (95% CI 94.0 to 82.7). Despite no overall change in volume of no levy drinks purchased , there was an increase in sugar purchased from no levy drinks of 15.3g (95% CI 12.6 to 17.9) per household per week, equivalent to 166.4% (95% CI 94.2 to 238.5). When all soft drinks were combined, there was no change in volume of drinks purchased at 12 months, but sugar purchased in drinks reduced by 29.5g (95% CI 55.8 to 3.1), or 9.8% (95% CI 17.9 to 1.8). There were no changes in purchases of confectionery or alcoholic drinks. Conclusions Compared to trends before the SDIL was announced, one year after implementation there was no change in the volume of soft drinks purchased, but the amount of sugar in those drinks was 30g, or 10%, lower per household per week - equivalent to one 250ml serving of low levy tier per person per week. The SDIL may represent a ‘win:win’ for public health and industry.