What is the deal with errors/warnings that are currently being tolerated?

In rare cases, there may be contradictions in the XRechnung standard that have not yet been finally clarified.

Especially with invoice types from the construction industry, the KoSIT Validator sometimes provides ambiguous results.

If you receive a message with the following content or the error code BR-CL-01 after validation, you can usually still send the XRechnung:

"The checked document contains at least one error / warning. It is NOT COMPLIANT with the formal requirements. It is recommended to process the document, as the existing errors/warnings are currently tolerated."

If your invoice recipient rejects the invoice and it is an XRechnung of an invoice type from the construction industry, you can, after consultation with the corresponding invoice recipient, use a different invoice type, e.g. "invoice".

What does the error message "If a 'Sales Order Reference' (BT-14) is specified, a 'Purchase Order Reference' (BT-13) must also be specified." or the error message "Document MUST not contain empty elements." mean?

The error message comes from the official KoSIT validator and states that the generated XRechnung contains an empty field, which is why the validation fails.

At the moment, "Sales Order Reference" and "Purchase Order Reference" are technically linked in such a way that if a "Sales Order Reference" (BT-14) is specified, a "Purchase Order Reference" (BT-13) must also be specified.

Even if we are not happy with this ourselves, we currently have to implement it this way, as the resulting invoice would otherwise not comply with the (technical) standard.

We are in contact with the authorities responsible for the standards in order to be able to offer a better solution in the future.

In short: If you specify a sales order reference, please always specify a purchase order reference as well. If your customer agrees, you can for example also enter a "-" as purchase order reference.

What does the error message "Error / Missing mandatory fields: Invalid content was found starting with element 'cac:Attachment'." mean?

The message indicates an error with the attachments of the invoice, most likely the ID/document identifier of the document is missing. According to the XRechnung specification, each attachment must have a document identifier.

Please check your entries in section "7 - Attachments" and create the invoice again. If empty attachments have accidentally been added during the processing of the attachments, they can simply be deleted.