How do I fix IS-R-004?

This requires user input to resolve. Review the relevant cbc: and cac: elements in your Invoice XML and provide the correct value. (IS-R-004). You can also use Invoice Navigator's compliance engine to correct this automatically in your pipeline.

Is IS-R-004 a critical error?

Yes, IS-R-004 is a critical error that will cause invoice rejection. It must be fixed before submission.

Can IS-R-004 be automatically fixed?

Many instances of IS-R-004 can be automatically corrected using Invoice Navigator's compliance engine. The fix is applied in your pipeline with full audit evidence.

errorISLCIUS-IS (Iceland)

`IS-R-004`:When both seller and buyer are Icelandic, the buyer's kennitala must be...

When both seller and buyer are Icelandic, the buyer's kennitala must be provided. This is required for domestic Icelandic transactions.

Severity

Fatal

Rule set

CIUS-IS (Iceland)

Country

ISL

Fix type

INPUT REQUIRED

Engine Classification

Business data required · Explicit input workflow · No assumptions made

Required input: Buyer Kennitala

What is IS-R-004?

IS-R-004 is a fatal validation rule defined in the CIUS-IS (Iceland) specification (ISL national rules). It checks whether when both seller and buyer are icelandic, the buyer's kennitala must be....

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.

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Why This Error Matters

Invoice will be rejected by Icelandic validation. Domestic transactions require buyer kennitala.

IS-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: IS-R-004
·Specification: CIUS-IS (Iceland)

Before / After

Failing XML

<Invoice>
  <!-- Issue: When both seller and buyer are Icelandic, the buyer kennital -->
</Invoice>

Corrected XML

<Invoice>
  <!-- Issue resolved per CIUS-IS (Iceland) -->
</Invoice>

Technical Reference

SpecCIUS-IS (Iceland)

StrategyRequires user input: Buyer kennitala (10 digits). User must provide buyer's Icelandic legal ID for domestic invoices.

Common Causes

·Buyer kennitala missing on domestic invoice
·Customer master data incomplete
·ERP does not enforce buyer ID for domestic
·Buyer legal ID field not populated
·Private consumer without kennitala

Seeing this in production? The API handles IS-R-004 automatically. See the fix response →

Related Errors

IS-R-002

Icelandic suppliers must provide their Icelandic legal ID (kennitala). This...

IS-R-003

Icelandic suppliers must provide complete address with street name and...

IS-R-005

When both seller and buyer are Icelandic, the buyer's address must include...

Last updated: 27 February 2026

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Handle IS-R-004 Automatically in Your Pipeline

The compliance engine auto-remediates this error with controlled safety policies and evidence pack generation.

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IS-R-004:When both seller and buyer are Icelandic, the buyer's kennitala must be...