In D365 FO, for a customer or vendor, in the Invoice and delivery section, you can enter a tax exempt number. Before you can do so, you must manually set up the tax exempt number.

In Data entry workflow, you can setup a data entry workflow template to create a customer or a vendor. For a data entry step in this template, you can select the Tax exempt number field.

When a data entry workflow is started, on data entry, you can enter any tax exempt number.

On transfer to target, if the entered tax exempt number:

• Exists, this number is used.
• Does not exist, it is automatically created.