Background The sales tax on all alcoholic drink was raised in Maryland from 6 to 9% on July 1, 2011. This study evaluates the effects of the alcohol sales tax increase on the rate of alcohol-involved drivers involved in fatal crashes.

Methods Study population: All drivers involved in a fatal motor vehicle crash in MD January 1, 2001 to December 31, 2013: 126 monthly data points from police reports pre-intervention and 30 post- intervention. Using an interrupted time series analysis we examined the effect of the tax on all alcohol-involved drivers in fatal crashes and fatally injured alcohol-involved drivers. Rates were calculated per 100,000 population, 100,000 licensed drivers, and 100 million vehicle miles travelled.

Results 6,967 crashes involving 10,777 drivers resulted in 4,642 driver fatalities. Unadjusted analysis found a significant 15% reduction in rate of alcohol-impaired drivers with BAC >0.08 g/dL per vehicle miles travelled after the tax increase. Significant reduction was also observed for alcohol-positive drivers and for fatally injured BAC positive drivers. After adjusting for linear trend, seasonality, and unemployment, the immediate effect of the 2011 alcohol sales tax increase in was not significant. However, we did observe a significantly larger decline in the rates of alcohol-impaired drivers and alcohol-related fatalities with BAC > 0.08 g/dL as indicated by the significant gradual decline in the slope after the introduction of the 2011 alcohol sales tax increase.

Conclusions While there was no immediate reduction in the rate of alcohol-impaired drivers following a 3% increase in alcohol sales tax, there was a significantly larger decline in the rates of alcohol-involved fatalities at BAC > 0.08 g/dL following the intervention, suggesting a gradual delayed effect. Other studies find an effect with excise taxes but this is the first study to evaluate the impact of sales taxes.