Sovos and order addons
The taxable status for sales order addons is set up based on State in SA Sales Use Taxes Setup-Addons. Each addon can be assigned to one of the SA Company Setup tax groups. Indicate the taxable status by selecting Yes or No for the taxability.
You should set up a tax group of 40000 in SA Company Setup and assign this group to all freight addons in SA Sales Use Taxes Setup for all state jurisdictions. With this setup, Sovos Sales and Use Tax recognizes the addon charge as freight and taxes appropriately.
The Sales and Use Tax System product code, 89999, indicates the charge should always be tax exempt. If you must create an addon that should always be tax exempt, in all jurisdictions, create a tax group 89999 and assign this tax group to the addon in SA Sales Use Taxes Setup-Addons.