warningEN 16931

`BR-55`:Prepayment should reference prepayment invoice

When PrepaidAmount is used, reference the prepayment invoice.

Severity

Warning

Rule set

EN 16931

Country

All EU

Fix type

INPUT REQUIRED

Engine Classification

Business data required · Explicit input workflow · No assumptions made

Required input: Prepayment Invoice Number

What is BR-55?

BR-55 is a warning validation rule defined in the EN 16931 specification. It validates the PrepaidPayment element under Invoice in the UBL invoice XML.

This is a soft validation failure. The invoice may pass initial transmission, but non-compliant values in this field can cause problems during tax audits, buyer-side processing, or downstream VAT reconciliation.

Target path: XPath: /Invoice/cac:PrepaidPayment

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Why This Error Matters

Invoice rejected. Credit notes and corrections must reference the original invoice for reconciliation.

BR-55 is a soft failure. The invoice may pass initial validation, but the non-compliant field can cause issues at the receiving end — tax authorities may flag it during audits, buyer ERP systems may fail to process it, or VAT reconciliation may produce mismatches. Fixing warnings before they accumulate prevents larger compliance gaps.

Validator Behavior

·Generates validation warning
·Error returned: BR-55
·Specification: EN 16931

How to Fix It

Add PrepaidPayment

If PrepaidAmount in totals

Reference invoice

ID of prepayment/advance invoice

Include amount

PaidAmount matches PrepaidAmount

Before / After

Failing XML

<Invoice>
  <!-- Issue: When PrepaidAmount is used, reference the prepayment invoice -->
</Invoice>

Corrected XML

<Invoice>
  <!-- Issue resolved per EN 16931 -->
</Invoice>

Technical Reference

XPathXPath: /Invoice/cac:PrepaidPayment

SpecEN 16931

StrategyRequires user input: The invoice number of the preceding/related invoice. Cannot derive because this references a specific external document.

Code Example

<cac:PrepaidPayment>
  <cbc:ID>ADV-2024-00123</cbc:ID>
  <cbc:PaidAmount currencyID="EUR">200.00</cbc:PaidAmount>
  <cbc:ReceivedDate>2024-11-01</cbc:ReceivedDate>
</cac:PrepaidPayment>
<cac:LegalMonetaryTotal>
  <cbc:PrepaidAmount currencyID="EUR">200.00</cbc:PrepaidAmount>
</cac:LegalMonetaryTotal>

Common Causes

·Preceding invoice reference section without invoice number
·BillingReference/InvoiceDocumentReference/ID empty
·Credit note referencing invoice but number not filled
·Template has reference structure but ID not mapped
·Related invoice number stored in wrong field

Seeing this in production? The API handles BR-55 automatically. See the fix response →

Commonly Seen In

All invoicing software

Frequently Asked Questions

When PrepaidAmount is used, reference the prepayment invoice.

Add PrepaidPayment with reference to prepayment. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.

BR-55 is a warning that may not always cause rejection, but it indicates a potential compliance issue that should be addressed to ensure full compatibility.

Many instances of BR-55 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including prepayment should reference prepayment invoice.

BR-55 is commonly seen in exports from All invoicing software. These software packages sometimes generate invoices that need adjustment to meet full compliance standards.

Related Errors

BR-13

Invoice total without VAT required

BR-CO-16

Payable amount calculation error

Last updated: 27 February 2026

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BR-55:Prepayment should reference prepayment invoice