# Create a Factur-X invoice PDF in C#

> Make a Factur-X or ZUGFeRD e-invoice in .NET, a PDF/A-3 file with the invoice XML attached and described in its metadata. MIT licensed, pure C#.

Available since 1.1.

Turn an invoice PDF and its XML into one Factur-X or ZUGFeRD hybrid invoice.

## Short answer

Draw or convert the invoice, attach its XML with `PdfInvoice.Attach` and the profile it follows,
then save as PDF/A-3b. The XML is checked for well formedness and embedded as `factur-x.xml`
with the relationship the profile calls for, and saving writes the Factur-X XMP metadata with its
extension schema.

```csharp
PdfFont font = PdfOpenTypeFont.Load("fonts/Inter-Regular.woff2");   // PDF/A needs embedded fonts
PdfDocument doc = PdfDocument.Create();
doc.Info.Title = "Invoice 42";
doc.Language = "en";
PdfPage page = doc.Pages.Add(PdfRectangle.A4);
using (PdfGraphics g = page.CreateGraphics())
{
    g.DrawString("Invoice 42", font, 24, PdfColor.Black, 72, 100);
    g.DrawString("Total: 1,210.00 EUR", font, 12, PdfColor.Black, 72, 130);
}

// The invoice XML from your billing system, in Cross Industry Invoice syntax.
byte[] xml = File.ReadAllBytes("invoice-42.xml");
PdfInvoice.Attach(doc, xml, PdfInvoiceProfile.EN16931);    // embedded as factur-x.xml
doc.Save("invoice-42.pdf", new PdfSaveOptions { Conformance = PdfConformance.PdfA3B });

PdfDocument check = PdfDocument.Open("invoice-42.pdf");
Console.WriteLine(string.Join(", ", check.Attachments.Select(a => a.Name)));
```

## Notes

- PDF/A needs embedded fonts, so the sample draws with an OpenType font rather than one of the
  standard 14. An invoice made with [HTML to PDF](https://www.jadev-corp.com/guides/html-to-pdf/) works the same way when
  its fonts are embedded.
- Profiles: `Minimum`, `BasicWL`, `Basic`, `EN16931`, `Extended` and `XRechnung`. PdfNetStack does
  not validate the XML against the profile's rules; check the invoice data before you attach it.
- To sign the invoice, sign the saved bytes last, see [Signatures](https://www.jadev-corp.com/guides/signatures/).

## Related

- [PDF/A](https://www.jadev-corp.com/guides/pdf-a/): levels, checks and the invoice options
- [Convert an HTML invoice to PDF](https://www.jadev-corp.com/recipes/html-invoice-to-pdf/)
- API: [PdfInvoice](https://www.jadev-corp.com/api/pdfnetstack/pdfinvoice/), [PdfInvoiceProfile](https://www.jadev-corp.com/api/pdfnetstack/pdfinvoiceprofile/), [PdfSaveOptions](https://www.jadev-corp.com/api/pdfnetstack/pdfsaveoptions/)

Source: https://www.jadev-corp.com/pdfnetstack/recipes/pdf-a-3-xml-attachment/