The addon allows you to specify tax classes per product attribute as opposed to the product as a whole. For example, Product A might be available in book or pdf format. Books are tax exempt but pdfs are taxable. In the default osCommerce installation you can only apply tax to the whole product. So, for this example, you can either apply tax to both books and pdfs or neither.

This addon lets you specify a tax class for each product attribute you add. For instance, Product A - hardcopy - no tax class; Product A - pdf - Taxable Goods.

If a tax class is applied to the product itself it will override any attribute tax classes. so if your product makes use of taxes per attribute, set your product tax class to '--none--' first.

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