PT-R-004:ATCUD validation code required
Portuguese invoices require ATCUD (unique document code).
Engine Classification
Financial or legal field · Modification blocked by policy
Reason: ATCUD (Código Único de Documento) requires a validation series registered with Autoridade Tributária. The code must be algorithmically generated by certified invoicing software using the registered series. You cannot manually add an ATCUD - ensure your invoicing software is AT-certified and has a valid series registered.
What is PT-R-004?
PT-R-004 is a fatal validation rule defined in the ubl-2.1 specification (PRT national rules). It validates the XPath: Extension or Note for ATCUD element in the UBL invoice XML.
When this rule fires, the invoice is non-compliant and will be rejected by Peppol access points and national validation services. The sending system receives a rejection response and the invoice does not reach the buyer.
Target path: XPath: Extension or Note for ATCUD
Why This Error Matters
ATCUD required for Portuguese invoice validity.
PT-R-004 is a hard failure. Invoices that trigger this rule are rejected at the access point and never reach the recipient. In Peppol networks, this means your sending system receives an MLR (Message Level Response) with a rejection status. The invoice must be corrected and re-sent, adding delay to your payment cycle.
Validator Behavior
- ·Causes invoice rejection
- ·Fails UBL schema validation
- ·Error returned: PT-R-004
- ·Specification: ubl-2.1
How to Fix It
Get ATCUD series
Register series with AT
Generate code
Series + document number
Add to invoice
Include ATCUD in document
XML Example
Generic example based on the rule's target XPath. Your actual XML structure may differ.
<!-- Triggers validation error --> <XPath: Extension or Note for ATCUD></XPath: Extension or Note for ATCUD>
<!-- Corrected --> <XPath: Extension or Note for ATCUD>VALID_VALUE</XPath: Extension or Note for ATCUD>
Technical Reference
XPath: Extension or Note for ATCUDCommon Causes
- ·Missing ATCUD
- ·Invalid ATCUD format
- ·Uncertified software
Seeing this in production? The API handles PT-R-004 automatically. See the fix response →
Frequently Asked Questions
Portuguese invoices require ATCUD (unique document code).
Add ATCUD code from certified software. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
Yes, PT-R-004 is a critical error that will cause invoice rejection. It must be fixed before submission.
Related Errors
Last updated: 27 February 2026
Handle PT-R-004 Automatically in Your Pipeline
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