Reference

BR-CO-20 Invoice line period needs a start or end date

If the invoice line period (BG-26) is used, the invoice line period start date (BT-134) or the invoice line period end date (BT-135) shall be filled, or both.

Problem Description

ERROR

EN 16931 calculation and consistency rule (BR-CO)

This EN 16931 rule is the line-level counterpart of BR-CO-19: an invoice line period (BG-26) must not be empty. Unlike the document level in UBL, a line period has no exception for cbc:DescriptionCode, because the VAT point date code (BT-8) exists only at document level. The error often occurs when an export creates a period element for every line, even for lines without a known period.

Solution

When a cac:InvoicePeriod appears inside an invoice line, provide at least a StartDate (BT-134) or an EndDate (BT-135); otherwise remove the empty element. In CII the line period is ram:SpecifiedLineTradeSettlement/ram:BillingSpecifiedPeriod.

Quick actions

Validate XML Convert invoice

Valid Examples

BT-134 = 2026-02-01 with BT-135 = 2026-02-28

Invalid Examples

Line cac:InvoicePeriod present but neither BT-134 nor BT-135 filled

Code Examples

Valid XML

<cac:InvoiceLine>
  <cac:InvoicePeriod>
    <cbc:StartDate>2026-02-01</cbc:StartDate>
    <cbc:EndDate>2026-02-28</cbc:EndDate>
  </cac:InvoicePeriod>
</cac:InvoiceLine>

Invalid XML

<cac:InvoiceLine>
  <cac:InvoicePeriod>
  </cac:InvoicePeriod>
</cac:InvoiceLine>

Affected Fields

BG-26 Invoice line period

BT-134 Invoice line period start date

BT-135 Invoice line period end date

Validation Tools

Official KoSIT Validator

Run the official KoSIT validator with the XRechnung configuration to check EN 16931 and XRechnung rules.

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