Where and how to change the code? At first, I thought overriding Mage_Catalog_Model_Product_Type_Configurable::getOrderOptions(). Original code change to However, it does not work. Then I tried to observe the event tax_rate_data_fetch and modify the rateRequest object. But inside rateRequest there is no reference to quoteItem. Only product tax_class_id is there. In the observer class, I do… Continue reading Change Magento configurable product to take associated products tax class