TaxJar API: How do I issue a sales tax only refund using the API?
We recommend the following steps to refund sales tax if you accidentally charged your customer sales tax and you shouldn't have.
1) Send in a full refund for the entire order to our API. This will ensure you properly get a refund on the sales tax if you have already had that tax remitted to the state. It will also make sure our reports properly handle the refund if the tax has yet to be remitted.
2) Once you have created the full refund, send in a new transaction that matches the original order but leave the sales tax parameter as $0.00. This way you can still report the sale but no tax will be created. Make sure you include either the product_tax_code that exempts the sale or include the customer_id that allows our API to know they are an exempt customer.