Customer Tax Exempt

I was talking with Michael about how We can have a customer Tax Exempt on the invoice. I was entering the information in the field of last name in Customer Profile so it would print on the invoice and be viewed on the Global Customer Data base so any store could verify without calling to verify. His concern it might not be able to be filtered out once we run a customer Profile Print out. We do have a line when We are adding a New Customer below the account number line that indicates Customer Tax, is this capable of being printed on the invoice and can it also be made to be viewed when looking up customer in the Data base that we now search? Or what does this field do?