@wes_w - frankly, not very much clear what is “checked” and what is not here - “sales orders shipping to addresses in Illinois set to our default tax code of -Not Taxable- for orders which were subject to Illinois sales tax based on the ‘Taxable’ field being checked and the ‘Tax Item’ field being empty on the customer record(s) in question”. Are IL customers set as Taxable? Are items set as Taxable? Are transactions line items for IL orders set as Taxable?