BR-CO-20

If a line period (BG-26) is sent on an invoice line, at least one date must be in it: the start (BT-134), the end (BT-135), or both. The line-level counterpart to BR-CO-19.

Severity: Error
Applies to: CII, UBL
Rule set: v2026-01-31

Official rule text

If 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.

Why does BR-CO-20 happen?

The same mistake as in the header, only more often: lines are produced in a loop and the period group is created for every one of them, though only some lines actually have a period.

How do you fix BR-CO-20?

Emit cac:InvoicePeriod inside cac:InvoiceLine only when a date exists — and in CII, ram:BillingSpecifiedPeriod inside the line, on the same condition.

In the XML

A UBL fragment. The CII path is named above — same change, different element names.

Fails

<cac:InvoiceLine>
  <cbc:ID>1</cbc:ID>
  <cbc:LineExtensionAmount currencyID="EUR">1000.00</cbc:LineExtensionAmount>
  <cac:InvoicePeriod/>
</cac:InvoiceLine>

Fixed

<cac:InvoiceLine>
  <cbc:ID>1</cbc:ID>
  <cbc:LineExtensionAmount currencyID="EUR">1000.00</cbc:LineExtensionAmount>
  <cac:InvoicePeriod>
    <cbc:StartDate>2026-08-01</cbc:StartDate>
    <cbc:EndDate>2026-08-31</cbc:EndDate>
  </cac:InvoicePeriod>
</cac:InvoiceLine>

NormAPI provides technical validation, not tax or legal advice.