Attachments

Introduction

It can sometimes be useful to include "external" attachments when sending documents. Common examples include:

a visual representation of the main document, e.g. a PDF
an image of scanned receipts or other objects that acts a base for the document
detailed time sheets
an image of a product

Below, we describe the various technical solutions that exist to provide this functionality.

Supported file types

The following attachment file types are supported by us:

File type | Extension | MIME type --------- | ---------- | ---------- PDF | .pdf | application/pdf JPEG | .jpg,
.jpeg | image/jpeg TIFF | .tif,
.tiff | image/tiff GIF | .gif | image/gif BMP | .bmp | image/x-bitmap SVG | .svg | image/svg+xm PostScript | .ps | application/postscript MS Excel | .xls,
.xlsx | application/vnd.ms-excel,
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet MS Word | .doc,
.docx | application/msword,
application/vnd.openxmlformats-officedocument.wordprocessingml.document MS Powerpoint | .ppt,
.pptx | application/ppt,
application/vnd.openxmlformats-officedocument.presentationml.presentation Plain text | .txt | text/plain RTF | .rtf | application/rtf CSV | .csv | text/csv EML | .eml | multipart/signed XML | .xml | application/xml, text/xml HTML | .html | text/html ZIP | .zip | application/zip P7M | .p7m | application/pkcs7-mime P7B | .p7b | application/pkcs7-mime P7S | .p7s | application/x-pkcs7-signature PK7 | .pk7 | application/x-pk7

Please note that it also depends on the receiver, their system capabilities and in some cases; the receiver's service provider as well.

Attachment file size

The industry recommendation is 5 MB for each attached file.

Multiple attachments

There is no limit in regards to how many attachments you can send; send as many as you'd like!

Presentation images

Providing an presentation/image of the electronic document is sometimes useful.

We support this where applicable, but please be aware that it might not always get forwarded to the receiver due to limitations in the target format or in the interoperability agreement between us and the receiver's service provider.

Warning

According to the European standard EN 16931-1:2017 for electronic invoicing, it is not allowed to include a visual representation of an invoice/credit note. Do note, however, that this only applies to invoice and credit notes.

As such, public entities/B2G receivers within EU have grounds to reject invoices which doesn't comply with this requirement.

Embedded

In a lot of modern formats, it is possible to include attachments within the actual main document. The only requirement is that they are Base64-encoded as binary objects.

This is the most elegant and failsafe way of including attachments.

More information on Base64 can be found here and here.

Examples

Peppol BIS Billing 3.0 example
<?xml version="1.0" encoding="UTF-8"?>
<Invoice ...>
    <!-- Omitted for clarity -->
    <cbc:ID>123456789</cbc:ID>
    <!-- Omitted for clarity -->
    <cac:AdditionalDocumentReference>
        <cbc:ID>987654321</cbc:ID>
        <cac:Attachment>
            <cbc:EmbeddedDocumentBinaryObject 
              filename="scanned_receipts.pdf" 
              mimeCode="application/pdf"
                >JVBERi0xLjMNCiXi48/TDQolUlNUWFBERjMgUGFyY
                ... 
                gMCBSDQo+Pg0Kc3RhcnR4cmVmDQoyNDIzMQ0KJTg==</cbc:EmbeddedDocumentBinaryObject>
        </cac:Attachment>
    </cac:AdditionalDocumentReference>
    <!-- Omitted for clarity -->
</Invoice>

IFS e-invoice 2.0 example
<?xml version="1.0" encoding="UTF-8"?>
<IFSFinvoice Version="2.0"...>
    <!-- Omitted for clarity -->
    <InvoiceDetails>
        <!-- Omitted for clarity -->
        <InvoiceNumber>123456789</InvoiceNumber>
    </InvoiceDetails>
    <InvoiceAttachments>
        <FileName>invoice_image.pdf</FileName>
        <DocumentType>ATS</DocumentType>
        <Attachment>JVBERi0xLjMKJaqrrK0KNCAwIG9iago8PCAvVHlwZSAvSW5mbwovUHJv
          MDAwIG4gCjAwMDAwNjcyOTMgMDAwMDAgbiAKMDAwMDA2NzQ0MCAwMDAwMCBuIAowMDAwMDY3OTM0
          ...
          IDAwMDAwIG4gCnRyYWlsZXIKPDwKL1NpemUgMjgKL1Jvb3QgMiAwIFIKL0luZm8gNCAwIFIKPj4K
          c3RhcnR4cmVmCjY5NTUwCiUlRU9GCg==
        </Attachment>
        <MimeType>pdf</MimeType>
        <Description>invoice_image_123</Description>
    </InvoiceAttachments>
</IFSFinvoice>

Batched attachments

Another way of sending attachments is by putting them aside the main document within a structure allowing for main document and attachment to be provided within the same file. One of the most common ways of doing this is by using a compressed folder. The .zip-archive is highly adopted and used.

The structure within the .zip-file should include the main document together with the corresponding attachments.

Example

Example directory structure within ZIP
invoice123.zip
\-- invoice123.xml
\-- invoice123_presentation.pdf
\-- invoice123_misc.xsls

It is important that the structure is/remains the same for every document sent.