IS-R-004:When both seller and buyer are Icelandic, the buyer's kennitala must be...
Fix: 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). Provide the required value in the free validator.
When both seller and buyer are Icelandic, the buyer's kennitala must be provided. This is required for domestic Icelandic transactions.
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).
When this rule fires, the invoice is rejected by Peppol access points and never reaches the buyer.
Why This Error Matters
Invoice will be rejected by Icelandic validation. Domestic transactions require buyer kennitala.
IS-R-004 is a hard failure — the invoice must be corrected and re-sent before it can reach the recipient.
Validator Behavior
- ·Causes invoice rejection
- ·Error returned: IS-R-004
- ·Specification: CIUS-IS (Iceland)
How to Fix It
Identify the missing data
When both seller and buyer are Icelandic, the buyer's kennitala must be provided. This is required for domestic Icelandic transactions.
Provide the required value
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).
Re-validate your invoice
Upload the corrected invoice to confirm IS-R-004 is resolved.
Before / After
<Invoice> <!-- Issue: When both seller and buyer are Icelandic, the buyer kennital --> </Invoice>
<Invoice> <!-- Issue resolved per CIUS-IS (Iceland) --> </Invoice>
Technical Reference
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 →
Frequently Asked Questions
When both seller and buyer are Icelandic, the buyer's kennitala must be provided. This is required for domestic Icelandic transactions.
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.
Yes, IS-R-004 is a critical error that will cause invoice rejection. It must be fixed before submission.
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.
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Last updated: 14 April 2026
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