Each Document level allowance (ibg-20) shall be categorized by Document level allowance tax category code（ibt-095）and Document level allowance tax rate（ibt-096).
/cac:AllowanceCharge[cbc:ChargeIndicator=true()]exists(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/cbc:ID) and exists(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/cbc:Percent)