HU-R-004:Hungarian VAT code required
NAV requires Hungarian-specific VAT category codes.
Engine Classification
Business data required · Explicit input workflow · No assumptions made
Required input: Hungarian VAT Category
What is HU-R-004?
HU-R-004 is a fatal validation rule defined in the nav specification (HUN national rules). It validates the XPath: Extension for NAV VAT code 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 for NAV VAT code
Why This Error Matters
NAV uses specific VAT categorization.
HU-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
- ·Error returned: HU-R-004
- ·Specification: nav
How to Fix It
Map VAT
EN16931 to Hungarian category
Add code
AAM, TAM, etc.
XML Example
Generic example based on the rule's target XPath. Your actual XML structure may differ.
<!-- Triggers validation error --> <XPath: Extension for NAV VAT code></XPath: Extension for NAV VAT code>
<!-- Corrected --> <XPath: Extension for NAV VAT code>VALID_VALUE</XPath: Extension for NAV VAT code>
Technical Reference
XPath: Extension for NAV VAT codeCommon Causes
- ·Missing Hungarian VAT code
- ·Wrong mapping
Seeing this in production? The API handles HU-R-004 automatically. See the fix response →
Frequently Asked Questions
NAV requires Hungarian-specific VAT category codes.
Map VAT category to Hungarian code. Invoice Navigator can help identify and fix this issue.
Yes, HU-R-004 is a critical error that must be fixed.
Related Errors
Last updated: 27 February 2026
Handle HU-R-004 Automatically in Your Pipeline
The compliance engine auto-remediates this error with controlled safety policies and evidence pack generation.