taxExempt flags a buyer who doesn't pay sales tax — typically a licensed dealer or resale buyer. When it's on, their invoices skip the tax amount. Only set it when you have a valid exemption certificate on file, recorded in the tax-exempt certificate field.
Marking a buyer tax exempt removes sales tax from their invoices. Set it only with a valid certificate on record, since it affects tax reporting.
Technical section
Data model, API, and internals — visible to developers.