Hi Robert, can you share the XRechnung you're trying to read? I think I had a similar problem and was able to fix it. Dave

Hello Mark,

I have the problem with writing the invoice. In the invoiceDescriptor22UblWriter.cs I have found following code:
foreach (var tax in taxRegistrations)
{
Writer.WriteStartElement("cac", "PartyTaxScheme");
Writer.WriteElementString("cbc", "CompanyID", tax.No);
Writer.WriteStartElement("cac", "TaxScheme");
Writer.WriteElementString("cbc", "ID", UBLTaxRegistrationSchemeIDMapper.Map(tax.SchemeID));
Writer.WriteEndElement(); //!TaxScheme
Writer.WriteEndElement(); //!PartyTaxScheme
}

So CompanyID will be writen with tax.No.

I'm using
desc.AddBuyerTaxRegistration(Beleg.KundenUID, TaxRegistrationSchemeID.VA);

to set the tax.no and scheme. But for any reason (I'm currently not able to debug the test code of the lib) the uid will be not set. Removing this field, will lead in a positive pass for validation in all tested validators.

Till this isse is clearified I'm a fix function, which fix multiple problems I have at the moment and also remove this empty CompanyID :

public static string FixUnsolvedBugs(string xmlInvoice, int BelegTypID)
{
// Define the lines to add for TaxExemption
string taxExemptionToAdd = @"
cbc:TaxExemptionReasonCodeVATEX-EU-I</cbc:TaxExemptionReasonCode>
cbc:TaxExemptionReasonlocal law</cbc:TaxExemptionReason>";

// Split the XML into lines for processing
List<string> updatedLines = new List<string>();
string[] lines = xmlInvoice.Split(new[] { "\r\n", "\n" }, StringSplitOptions.None);

bool insideTaxCategory = false; // Flag to track if we're inside the correct node

foreach (string line in lines)
{
    // Exclude the unwanted line "<cbc:CompanyID />"
    if (line.Contains("<cbc:CompanyID />"))
    {
        continue;
    }

    // Detect the start of a TaxCategory node
    if (line.Contains("<cac:TaxCategory>"))
    {
        insideTaxCategory = true;
    }

    // Detect the end of a TaxCategory node
    if (line.Contains("</cac:TaxCategory>"))
    {
        insideTaxCategory = false;
    }

    // Add the current line to the updated list
    updatedLines.Add(line);

    // If inside TaxCategory and line contains "<cbc:Percent>0.00</cbc:Percent>", add TaxExemption lines
    if (insideTaxCategory && line.Contains("<cbc:Percent>0.00</cbc:Percent>"))
    {
        updatedLines.AddRange(
            taxExemptionToAdd.Trim().Split(new[] { "\r\n", "\n" }, StringSplitOptions.None)
        );
    }
}

// Rejoin the updated lines into the final XML string
string finalXML = string.Join("\n", updatedLines);
// credit note fixes
if (BelegTypID == 8)
{
    finalXML = finalXML.Replace("<cbc:InvoiceTypeCode>381</cbc:InvoiceTypeCode>", "<cbc:CreditNoteTypeCode>381</cbc:CreditNoteTypeCode>");
    finalXML = finalXML.Replace("InvoiceLine", "CreditNoteLine");
    finalXML = finalXML.Replace("InvoicedQuantity", "CreditedQuantity");
}
return finalXML;

}

With this fix I will pass all validations in extended and XRechnung Mode for UBL for invoice and credit notes. Also credit notes are not working as needed for me in the libary. I.e. needed param like CreditNoteLine_ are not part of the libary- or let's say, I was not able to find the term in the lib.

CIAO Robert