Background : The WHO recommends soda taxes to reduce sugar consumption, but the effect across socioeconomic groups is unclear. Objectives : We assessed 16-y trends in daily soda consumption among adolescents in 4 European countries with a soda tax and 5 comparison countries, by family affluence. Methods : Five rounds of the international “Health Behaviour in School-Aged Children” school-based survey were used (school years 2001/2002 to 2017/2018, repeated cross-sectional design). Finland, France, Belgium, and Portugal introduced or updated a soda tax during this period. For comparison, we selected 5 neighboring countries without such a tax. Nationally representative samples of adolescents aged 13 and 15 y (n = 165,521; 51.2% girls) completed a standardized questionnaire, including a question on soda consumption frequency. Using the family affluence scale (FAS), we categorized adolescents into lower-, middle- or higher-affluent groups. Changes in daily soda consumption were assessed in each country independently. Results : Before taxation, daily soda consumption was more likely among lower-affluent adolescents in France and Belgium (P < 0.001, socioeconomic inequalities) and was similar across FAS groups in Finland and Portugal (no inequalities). After the tax, daily soda consumption was reduced across all FAS groups in Finland, Belgium, and Portugal (Pinteractions ≥ 0.33). In France, a posttax decrease was observed only among lower-affluent adolescents (ORlower, 0.76; 95% CI: 0.60, 0.96; reduced inequalities). During the same periods, socioeconomic patterns remained stable in 3 comparison countries (Pinteractions ≥ 0.38), and larger reductions in daily soda consumption were observed among middle- or higher-affluent adolescents compared with lower-affluent adolescents in the remaining 2 comparison countries (Pinteractions ≤ 0.08, increased inequalities). Conclusions : Socioeconomic patterns did not change after the tax implementation in 3 out of 4 countries, and socioeconomic inequalities were reduced in France. Taxing sodas might be an effective measure to attenuate, or at least not exacerbate, socioeconomic inequalities in adolescent daily soda consumption.