With tax free season coming around, majority of my Magento clients requested that products set to specific categories be made tax free.

Magento sets the tax_class_id attribute on the product level, which would require me doing a batch update of the products, however I can’t set a filter to specific categories which puts me back to square one.

Below is a simple SQL query that will update all products to a Tax Class of None, based on a set of category ids I define.

WARNING: Always do a complete database backup before running SQL queries against your database

UPDATE catalog_product_entity_int cpei
SET cpei.value = 0
WHERE cpei.attribute_id = (SELECT attribute_id FROM eav_attribute WHERE attribute_code = 'tax_class_id')
AND cpei.value = 2
AND cpei.entity_id IN (
    SELECT product_id AS entity_id FROM catalog_category_product
    WHERE category_id IN (1,2,3,4,5,6,7,8,9)
  )

Be sure to replace this section

WHERE category_id IN (1,2,3,4,5,6,7,8,9)

to include the comma separate list of category_id values you wish to apply this to.

You can also change the tax_class_id you set these products to by modifying this line:

SET cpei.value = 0

. Change the 0 to the value of the tax_class_id you wish to set it to.

After applying the SQL query, be sure to update the Product Flat Data under System > Index Management, then refresh all of your Magento caches under System > Cache Management