BT-42Seller contact telephone number
Official rule text
[BR-DE-27] BT-42 shall contain at least three digits.
Official text (German): In BT-42 sollen mindestens drei Ziffern enthalten sein.
Why this error occurs
XRechnung checks that the seller contact telephone number (BT-42) looks like a real number: it must contain at least three digits. The rule matches cbc:Telephone in the seller cac:Contact (UBL) or ram:TelephoneUniversalCommunication/ram:CompleteNumber (CII) against a regular expression. It fires on placeholders such as "-", "n/a", "on request" or on fields filled with text, which software sometimes emits to satisfy the mandatory-field rule BR-DE-6.
How to fix it
Enter a real telephone number with at least three digits, preferably in international format: +49 30 1234567. Spaces, hyphens, slashes and brackets are tolerated, but the digits must be there. Do not use placeholder text; if no direct line exists, give the switchboard number. This is a warning, but receivers may reject on it.
Example (valid)
<cbc:Telephone>+49 30 1234567</cbc:Telephone>What the validator checks
Checked element (context):
UBL
/ubl:Invoice/cac:AccountingSupplierParty/cac:Party/cac:Contact | /cn:CreditNote/cac:AccountingSupplierParty/cac:Party/cac:ContactTest (XPath):
matches(normalize-space(cbc:Telephone), $XR-TELEPHONE-REGEX)CII
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SellerTradeParty/ram:DefinedTradeContactTest (XPath):
matches(normalize-space(ram:TelephoneUniversalCommunication/ram:CompleteNumber), $XR-TELEPHONE-REGEX)Check your invoice
Drop your XML or PDF on the validator and every failed rule is linked to its page here. Free, no account, the file is not stored.
Same check via API:
curl -F file=@invoice.xml https://einvoicechecker.com/v1/validateRelated rules
BR-DE-6Seller contact telephone number (BT-42) is missingBR-DE-1Payment instructions (BG-16) are missingBR-DE-2Seller contact (BG-6) is missingBR-DE-3Seller city (BT-37) is missingBR-DE-4The element "Seller post code" must be transmittedBR-DE-5Seller contact point (BT-41) is missingBR-DE-7Seller contact email address (BT-43) is missingBR-DE-8The element "Buyer city" must be transmitted
Frequently asked questions
What does BR-DE-27 mean?
BR-DE-27 is a xrechnung rule: BT-42 shall contain at least three digits.
Will my invoice be rejected because of BR-DE-27?
No. BR-DE-27 is a warning: the invoice is accepted but the recipient sees the notice. Fix it anyway, warnings often become errors in later rule versions.
Which formats does BR-DE-27 apply to?
XRechnung in UBL or CII syntax, including ZUGFeRD / Factur-X PDFs with the XRECHNUNG profile. Invoices to German public authorities (federal, state and municipal) must pass it. Syntax: UBL and CII.
Source: XRechnung 3.0.2, schematron 2.6.0 (KoSIT, September 2026). Catalogue generated from the official schematron on 2026-10-14.