Amazon items are marked with one of two tax codes:
The tax settings are configured in the Amazon account settings. However, products are tagged on the product level by selecting a tax code. The tax code selection is selected on the Amazon Properties page.
If your products are displaying the wrong tax code in Seller Central, update the field in SellerCloud and relaunch the product.
To update products in bulk in SellerCloud, use the column header AmazonTaxCode. The expected values are the stated codes above. Once the bulk update is completed, re-post the products to Amazon.