How to Read a UBL Invoice XML: Element-by-Element Guide

Quick answer: how to read a UBL invoice

The quickest way is to drop the file into a UBL Invoice Viewer, which lays it out like a normal invoice. If you want to read the XML itself, start at the top: the header elements (cbc:ID, cbc:IssueDate, cbc:DocumentCurrencyCode) tell you which invoice it is, the two party blocks tell you who sent it to whom, and cac:LegalMonetaryTotal near the end tells you what to pay.

Direct answer: cbc = a single value, cac = a group of values. Read ID and dates first, then AccountingSupplierParty and AccountingCustomerParty, then TaxTotal, LegalMonetaryTotal and the InvoiceLine elements.

cbc and cac: the two prefixes

UBL uses XML namespaces. Elements with the cbc: prefix (Common Basic Components) hold one value, such as <cbc:IssueDate>2026-02-15</cbc:IssueDate>. Elements with cac: (Common Aggregate Components) are containers, such as <cac:PostalAddress>, which hold other elements. Amounts carry their currency as an attribute: <cbc:PayableAmount currencyID="EUR">2420.00</cbc:PayableAmount>.

Walking through a UBL invoice from top to bottom

• CustomizationID and ProfileID: which rule set applies, e.g. Peppol BIS Billing 3.0.
• cbc:ID, cbc:IssueDate, cbc:DueDate: invoice number and dates.
• cbc:InvoiceTypeCode: 380 for an invoice. Credit notes use a CreditNote root with code 381.
• cbc:DocumentCurrencyCode and cbc:BuyerReference: currency and the buyer's reference.
• cac:AccountingSupplierParty / cac:AccountingCustomerParty: cbc:EndpointID (Peppol ID), cac:PartyName, cac:PostalAddress, cac:PartyTaxScheme/cbc:CompanyID (VAT ID), cac:PartyLegalEntity/cbc:RegistrationName (legal name).
• cac:PaymentMeans: code 58 = SEPA credit transfer, cbc:PaymentID = payment reference, cac:PayeeFinancialAccount/cbc:ID = IBAN.
• cac:TaxTotal: total VAT, then one cac:TaxSubtotal per VAT rate with taxable amount, VAT amount and category (S = standard rate).
• cac:LegalMonetaryTotal: LineExtensionAmount (sum of lines), TaxExclusiveAmount (net), TaxInclusiveAmount (gross), PayableAmount (to pay).
• cac:InvoiceLine: per line cbc:InvoicedQuantity with unitCode (HUR = hour, C62 = piece), cbc:LineExtensionAmount, cac:Item/cbc:Name and cac:Price/cbc:PriceAmount.

Check that the numbers add up

In a correct invoice, the line amounts add up to LineExtensionAmount, TaxExclusiveAmount plus the VAT total equals TaxInclusiveAmount, and TaxInclusiveAmount minus any PrepaidAmount equals PayableAmount. The PEPPOL Invoice Validator does these sums for you and shows which rule fails.

Practice on a real file: download the sample Peppol BIS 3.0 invoice, open it in a text editor next to the UBL Invoice Viewer, and match each value on the invoice to its element.