{
  "id": "BR-29",
  "country": "EU",
  "syntax": "ubl",
  "group": "document",
  "severity": "fatal",
  "severity_note": "fatal, from the Flag column of the Peppol BIS Billing 3.0 UBL rules index retrieved 2026-10-18.",
  "spec": "Peppol BIS Billing 3.0, May 2026 release, EN 16931 model bound to UBL",
  "statement": "If both Invoicing period start date (BT-73) and Invoicing period end date (BT-74) are given then the Invoicing period end date (BT-74) shall be later or equal to the Invoicing period start date (BT-73).",
  "statement_lang": "en",
  "context": "cac:InvoicePeriod",
  "test": "(exists(cbc:EndDate) and exists(cbc:StartDate) and xs:date(cbc:EndDate) >= xs:date(cbc:StartDate)) or not(exists(cbc:StartDate)) or not(exists(cbc:EndDate))",
  "meaning": "If both the invoicing period start date (BT-73) and the invoicing period end date (BT-74) are given, the invoicing period end date (BT-74) must be later or equal to the invoicing period start date (BT-73). The message says \"shall be later or equal to\" and ends with a period. The context is the invoice period, not an invoice line period. The published test compares the two dates with xs:date and passes when either date is absent. The comparison has spaces around >=. Both absent branches call exists.",
  "fix": "When both invoicing period dates are present, set the end date (BT-74) on or after the start date (BT-73).",
  "example_fail": "Both invoicing period dates are present, and the end date is before the start date.",
  "example_pass": "The end date is on or after the start date, or at least one of the two dates is absent.",
  "example_note": "Illustration of the condition in the official statement. Not an example published by the source.",
  "source_url": "https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/BR-29/",
  "source_retrieved": "2026-10-18",
  "last_verified": "2026-10-18"
}