As of July 1 2018, thirty-seven, states currently charge sales tax on diapers. This tax can range from 2.9% in Colorado to 7.25% in California, and in many states, cities and counties can add additional tax. Children require at least 50 diaper changes per week, or 200 diaper changes per month. By reducing the sales tax, families can buy 2 additional diapers for every percentage point reduction in the sales tax for the same money they would have used to buy 200 diapers with tax. To see the full list of diaper sales tax laws for all 50 states, download our sales tax survey here. (last updated July 2, 2018) Sales Tax Survey Jul 2018