The VAT category tax amount (BT-117) In a VAT breakdown (BG-23) where the VAT category code (BT-118) equals "Exempt from VAT" shall equal 0 (zero).
/*/cac:TaxTotal/cac:TaxSubtotal/cac:TaxCategory[normalize-space(cbc:ID) = 'E'][cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']xs:decimal(../cbc:TaxAmount) = 0