Twenty-six states and the District of Columbia tax these two fuel types at the same rate or very similar rates, as of April 2019, according to data from the American Petroleum Institute.
The other 24 states levy tax rates that vary by 1 cent per gallon, or more, across fuel types. Among those states, diesel tax rates are usually higher than gasoline taxes so that heavy trucks producing more wear-and-tear on the roads will pay more toward infrastructure maintenance.
But seven states (Colorado, Delaware, Florida, Kentucky, Montana, Nevada, and Tennessee) assess a significantly lower rate on diesel fuel than gasoline, which raises questions as to whether heavy trucks are paying their fair share. Kentucky, however, requires commercial carriers to pay a surtax that helps lessen the inequity associated with taxing diesel fuel at a lower rate than gasoline.