How does SmartCalcs work?
TaxJar's SmartCalcs takes the state from which you ship (or the state in which you have nexus) amount, shipping charged, city and zip-code from which you ship (or from the state in which you have nexus) city and zip-code shipped-to as input and returns the amount of sales tax that should be withheld.
SmartCalcs determines the rate based on city and zip-code (including plus 4 information), taking into account whether or not the state in question is origin-based or destination based and whether or not shipping is taxable.
SmartCalcs also supports item taxability. Certain products, including dietary supplements, clothes and food are taxed at a reduced rate in some states and are sometimes even tax exempt. From clothing in New York to food in California, TaxJar's SmartCalcs Sales Tax API supports special sales tax circumstances for the products you sell.