In a VAT breakdown (BG-23) where the VAT category code (BT-118) is "Reverse charge" the VAT category taxable amount (BT-116) shall equal the sum of Invoice line net amounts (BT-131) minus the sum of Document level allowance amounts (BT-92) plus the sum of Document level charge amounts (BT-99) where the VAT category codes (BT-151, BT-95, BT-102) are "Reverse charge".
/*/cac:TaxTotal/cac:TaxSubtotal/cac:TaxCategory[normalize-space(cbc:ID) = 'AE'][cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT'](exists(//cac:InvoiceLine) and (xs:decimal(../cbc:TaxableAmount) = (sum(../../../cac:InvoiceLine[cac:Item/cac:ClassifiedTaxCategory/normalize-space(cbc:ID)='AE']/xs:decimal(cbc:LineExtensionAmount)) + sum(../../../cac:AllowanceCharge[cbc:ChargeIndicator=true()][cac:TaxCategory/normalize-space(cbc:ID)='AE']/xs:decimal(cbc:Amount)) - sum(../../../cac:AllowanceCharge[cbc:ChargeIndicator=false()][cac:TaxCategory/normalize-space(cbc:ID)='AE']/xs:decimal(cbc:Amount))))) or (exists(//cac:CreditNoteLine) and (xs:decimal(../cbc:TaxableAmount) = (sum(../../../cac:CreditNoteLine[cac:Item/cac:ClassifiedTaxCategory/normalize-space(cbc:ID)='AE']/xs:decimal(cbc:LineExtensionAmount)) + sum(../../../cac:AllowanceCharge[cbc:ChargeIndicator=true()][cac:TaxCategory/normalize-space(cbc:ID)='AE']/xs:decimal(cbc:Amount)) - sum(../../../cac:AllowanceCharge[cbc:ChargeIndicator=false()][cac:TaxCategory/normalize-space(cbc:ID)='AE']/xs:decimal(cbc:Amount)))))