Based on current US state tax laws, Swappa is required to calculate and collect sales tax for transactions destined to states where marketplace facilitator taxes apply. Swappa keeps a list of these states on Swappa's primary taxes page here.

Swappa does not charge any additional fees for calculating taxes, and the collection process applies to all sales on Swappa regardless of where the seller is located, as this is generally calculated according to the buyer’s shipping address. However, some states may calculate taxes based on where the seller is located. Read more here.