SummaryBackgroundIn Mexico, a 10% tax to sugar‐sweetened beverages was implemented in 2014. Projections of the potential health effect of this tax in children are not available.ObjectiveTo estimate the 1‐year effect of the tax on the body weight of children 5 to 17 years old, and estimated alternative scenarios with higher tax rates (20%, 30%, and 40%).MethodsWe used a dynamical mathematical model, recalibrated to the Mexican population. Input data were obtained from the Mexican National Health and Nutrition Survey 2006 and 2012. We estimated the expected average weight reduction, stratified by category of sugar‐sweetened beverages consumption.ResultsWith a 10% tax, we estimated an overall weight reduction of 0.26 kg for children and 0.61 kg for adolescents; in high consumers, the reduction could reach 0.50 and 0.87 kg, respectively. Higher tax rates would produce larger weight decreases; in high consumers a 40% tax would result in a reduction of 1.99 kg for children and 3.50 kg for adolescents.ConclusionThe tax represents an effective component of any child or adolescent weight control program, and must be considered as part of any integrated population‐level program for children and adolescent obesity prevention.