INTRODUCTION: Raising tobacco prices via increased taxation may be undermined by tobacco industry tactics to keep budget cigarettes on the market. Price differentials between budget and premium cigarettes allow smokers to trade down in the face of average price rises thus attenuating health benefits. This study examines global trends of price differentials and associations with taxation. METHODS: Ecological analysis of country-level panel data of 195 countries' price differentials was performed and compared against total, specific excise, ad valorem and other taxation. Price differentials were expressed as the difference between budget cigarette and premium pack prices (as % of premium pack prices). Two-level linear regression models with repeated measurements (2014, 2016 and 2018) nested within each country assessed the association between country-level taxation structures and price differentials, adjusted for year, geographical region and income group. RESULTS: Worldwide, median price differential between budget and premium 20-cigarette packs was 49.4% (IQR 25.9%-70.0%) in 2014 and 44.4% (IQR 22.5%-69.4%) in 2018 with significant regional variation. The largest price differentials in 2018 were in Africa, with the lowest in Europe. Total taxation was negatively associated with price differentials (-1.5%, 95% CI -2.5% to -0.4% per +10% total taxation) as was specific excise taxation (-2.5%, 95% CI -3.7% to -1.2% per +10% specific excise tax). We found no statistically significant association between ad valorem taxation and price differentials. CONCLUSION: Total levels of taxation and specific excise taxes were associated with smaller price differentials. Implementing high specific excise taxes may reduce price differentials and improve health outcomes.