Tax Classes are stored as a BillMax List.
Depending on whether the customer is exempt from all taxes or an individual tax, will determine the setup.
Validation of the Tax Group settings validates the structure of the settings with respect to Tax Regions and Products sold. It does not validate the data entered, IE. it will not validate tax rates.
Taxes are charged based on a Tax Group derived from the User’s Tax Region and the Tax Class of the item or service. Tax Regions are set on an Account and inherited on the User. Tax Regions can be overridden on the User.
Method to list Tax Group settings sorted by Tax Class or Tax Region