TAX_EXEMPT_FLAG in RA_INTERFACE_LINES_ALL

For line_type = 'LINE',  the value entered in TAX_EXEMPT_FLAG column controls how a line is taxed.  Enter 'E' if you want AutoInvoice to exempt an invoice line that would normally be taxed and your system option 'Use Customer Exemptions' is set to Yes.  If you enter 'E'  you must enter a value in TAX_EXEMPT_REASON_CODE or TAX_EXEMPT_REASON_MEANING, depending on your batch source option setup.

FYI: When tax_exempt_flag = 'S' then tax will be calculated as per the normal procedures set up in Receivables.