BR-48
Each VAT breakdown (BG-23) shall have a VAT category rate (BT-119), except if the Invoice is not subject to VAT.
What the rule checks
As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.
cac:TaxTotal/cac:TaxSubtotal
exists(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/cbc:Percent) or (cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/normalize-space(cbc:ID)='O')
Checked with EN 16931 Invoice (UBL), EN 16931 Credit Note (UBL), Croatia eRačun Invoice (UBL), Croatia eRačun Credit Note (UBL)
//ram:ApplicableHeaderTradeSettlement/ram:ApplicableTradeTax
(.[upper-case(ram:TypeCode) = 'VAT']/ram:RateApplicablePercent) or (.[upper-case(ram:TypeCode) = 'VAT']/ram:CategoryCode = 'O')
Checked with EN 16931 Invoice (CII)
//ram:ApplicableHeaderTradeSettlement/ram:ApplicableTradeTax
(ram:RateApplicablePercent) or (ram:CategoryCode = 'O')
Checked with France Factur-X BASIC WL, Factur-X / ZUGFeRD BASIC WL