To configure a tax rate specifying a tax class:
Open the Taxes page of your store's Admin area.
X-Cart 5.4.x - Store Setup > Taxes
X-Cart 5.5.x - Store > Taxes
Then, open the appropriate tax configuration tab depending on the tax system you are using (possible variants are Sales Tax / VAT/GST / Canadian Taxes).
Locate the page section for the tax rates setup and click the New rate button.
In our example, it will be the "General Tax Rates" section of the Sales Tax add-on configuration page:
Configure tax rates by specifying the parameters below. Pay special attention to the "Tax class" selector.
Zone: Select the address zone to which the tax rate should apply.
Tax class: Select the tax class to which the tax rate should apply.
Rate: Specify the tax rate (in %).
Attention the Sales Tax add-on users: To set up a tax rate that will be used exclusively for shipping, use the section "Tax rates on shipping cost." Tax rates configured via the "General Tax Rates" section apply to products only.
Click Save changes.
That's it. Now you can use the created tax rate to assign it to a product or a shipping method.