Message

A VAT breakdown (BG-23) with VAT Category code (BT-118) " Not subject to VAT" shall have a VAT exemption reason code (BT-121), meaning " Not subject to VAT" or a VAT exemption reason text (BT-120) " Not subject to VAT" (or the equivalent standard text in another language).

Context
/*/cac:TaxTotal/cac:TaxSubtotal/cac:TaxCategory[normalize-space(cbc:ID) = 'O'][cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']
Test
exists(cbc:TaxExemptionReason) or (exists(cbc:TaxExemptionReasonCode) )
Usage
/ ubl:Invoice / cac:TaxTotal / cac:TaxSubtotal / cac:TaxCategory / cbc:ID
/ ubl:Invoice / cac:TaxTotal / cac:TaxSubtotal / cac:TaxCategory / cbc:TaxExemptionReasonCode
/ ubl:Invoice / cac:TaxTotal / cac:TaxSubtotal / cac:TaxCategory / cbc:TaxExemptionReason
/ ubl:CreditNote / cac:TaxTotal / cac:TaxSubtotal / cac:TaxCategory / cbc:ID
/ ubl:CreditNote / cac:TaxTotal / cac:TaxSubtotal / cac:TaxCategory / cbc:TaxExemptionReasonCode
/ ubl:CreditNote / cac:TaxTotal / cac:TaxSubtotal / cac:TaxCategory / cbc:TaxExemptionReason