What it means
For a Greek seller, the XPath selects seller cac:PartyTaxScheme entries whose cac:TaxScheme/cbc:ID is VAT after whitespace normalisation. Those entries must contain exactly one cbc:CompanyID in total. Its first two characters must be EL, not GR, and the remaining value must pass the Greek TIN check. This rule has warning severity.
Why it matters
The required format identifies the seller using a Greek VAT number in the VAT tax entry. A number recorded only in another field does not satisfy this check, and warning severity says nothing about the recipient's acceptance decision.
How to fix it
Confirm your Greek TIN against your tax details. Enter EL followed by its nine digits, without repeating the prefix, in cac:AccountingSupplierParty/cac:Party/cac:PartyTaxScheme/cbc:CompanyID. Set that tax entry's cac:TaxScheme/cbc:ID to VAT and remove duplicate seller VAT number entries. Check the corrected file again.
Once the file is corrected, check it again for free: Validate a Peppol BIS invoice
Or fix the invoice in a form and download the corrected file, for 1 credit: Fix a rejected e-invoice
The rule as published
Read the rule on the publisher's site
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 GR-S-011 still fails, and which other rules do.