Objectives South Korea implemented an unprecedented cigarette tax increase in 2015, raising its cigarette price by 80%. This study evaluated the extent to which the 2015 cigarette tax increase affected Korean adult smokers in terms of quit attempts, successful quitting and smoking intensity.

Methods Data were drawn from a nationally representative longitudinal study, the Korean Welfare Panel Study (waves 9–12, 2014–2017). Korean adults who smoked before the 2015 cigarette tax increase comprised the sample (n=2114). We used the multiple logistic regressions to examine factors of quit attempts and successful quitting and the generalised estimating equations to estimate changes in smoking intensity among continued smokers.

Results After the cigarette tax increase, 60.9% (n=1334) of baseline smokers attempted to quit and 34.7% of the attempters succeeded in quitting. The smokers aged ≥ 65 years and light smokers both attempted more (p<0.01) and succeeded more (p<0.05) in quitting than smokers aged 35–44 years and heavy smokers, respectively. The successful quitting was not significantly associated with income levels. Depressive symptoms, first cigarette use before age 19 and smoking a pack or more a day at baseline were associated with failures in quitting. Smoking intensity among continued smokers decreased after the cigarette tax increase (p<0.001), but such a decrease was not observed in light smokers, young smokers and high-income smokers.

Conclusion The current study findings imply that the Korean government may consider implementing periodic increases in cigarette tax which should reflect the rate of inflation and income growth. Smoking cessation programmes need to address depressive symptoms.