What it means
When the seller is Icelandic and the invoice carries an eindagi, the final payment date, it must be exactly 10 characters and a real calendar date in the form YYYY-MM-DD. The eindagi is given as an additional document reference (BT-122) whose description is EINDAGI, and the identifier of that reference holds the date. A date written 15/12/2026 fails, and so does a date that does not exist, such as 30 February. If there is no EINDAGI reference, the rule does not apply.
Why it matters
The recipient's software reads this field to find the final payment date. A value that is not a clean date cannot be read, so the Icelandic rules treat it as an error and the invoice is rejected.
How to fix it
Find the field in your invoicing software where the eindagi is set and enter the date as year, month and day with hyphens, for example 2026-12-15. If you build the XML yourself, put it in cbc:ID of the cac:AdditionalDocumentReference whose cbc:DocumentDescription is EINDAGI. Use a date that exists and leave out any time or extra text.
The rule as published
Read the rule on the publisher's site
Business terms: BT-122
Where this rule applies
| Rule set | Version |
|---|---|
| Peppol BIS Billing 3.0 (invoice) | 2026.5 |
| Peppol BIS Billing 3.0 (credit note) | 2026.5 |
Check your file
Drop your e-invoice to see whether IS-R-008 still fails, and which other rules do.
Related rules
- BR-52 Document reference is required
- BR-RO-L0308 Supporting document and object references: 200 characters at most
- IS-R-009 An invoice with an Icelandic eindagi also needs a due date
- IS-R-010 The Icelandic eindagi cannot be earlier than the due date
- IS-R-007 Bank transfers from Icelandic sellers need a 12-digit account
- IS-R-006 Payment code 9 for Icelandic sellers needs a 12-digit account