Items in AvaTax should have both a tariff code and a tax code to ensure that imported and exported products are taxed properly when shipped between countries. Stored tariff code assignments are included in tax calculations, whether that's in AvaTax or in the customer checkout experience via a supported integration.
Avalara Item Classification
You can provide
itemCode values for each
CreateTransaction() API call rather than specifying tax codes, parameters, descriptions, and other data fields. AvaTax will automatically look up each
itemCode and apply the correct tax codes and parameters from the item table instead. If an item doesn't exist, a new record is created. Existing items are updated. To set a field's value to null, you may either set its value to null or omit that field from the object you post.
AvaTax Item REST API instructions:
When passing via the classifications model, use the HS Code for the productCode field and the appropriate Tariff System Code in the systemCode field.