How do I manage default tax exemption handling for invoice lines?

If you update the default tax exemption handling value at the transaction level, this value becomes the default value for any new transaction lines created. You can change this default value on the new lines created at the line level.

Updating the default tax exemption handling value at the transaction level doesn't change the value on existing lines. If the transaction already contained transaction lines when you updated the default tax exemption handling value, these lines retain their existing tax exemption handling values.