What it means
When the seller and the buyer are both in Germany, the seller contact telephone number (BT-42) should be a valid telephone number. The official text asks for at least three digits. The check runs on the telephone entry in the seller's contact block, so an empty or missing number does not pass.
Why it matters
The contact number lets the buyer reach someone with questions about the invoice. A placeholder or a typo does not help them. Nothing is blocked because the rule is a warning, but it is easy to avoid.
How to fix it
In your invoicing software, open your company settings or the contact person shown on the invoice and check the telephone field. Enter a full number, ideally with the country code, such as +49 30 1234567. Remove placeholder text such as n/a or tel.
The rule as published
Read the rule on the publisher's site
Business terms: BT-42
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 DE-R-027 still fails, and which other rules do.
Related rules
- BR-DE-6 Seller contact phone is required
- BR-DE-27 The seller's phone number should contain at least three digits
- BR-RO-L1005 Seller contact phone number must be 100 characters or fewer
- DE-R-006 A seller phone number is required between German parties
- DE-R-028 Seller contact email address should be well formed
- DE-R-030 Direct debit needs the seller's creditor identifier