Consumption sales taxes are regressive in terms of annual income, but the shortcomings of annual data motivate analysis of tax incidence over a longer time interval. Two widely read public finance textbooks contain mistakes regarding the^effect of different lifetime consumption profiles on consumption sales tax proportionality. This paper concludes that consumption sales taxes would be proportional in lifetime terms if all individuals eventually consumed their entire lifetime incomes. However, monetary gifts and bequests escape the tax and make horizontal inequities and lifetime non-proportionality likely. Augmenting the tax with equal-rate taxes on gifts and bequests would ensure lifetime proportionality among all individuals regardless of their lifetime consumption profiles, gift givings, and estates.