Emailing an invoice with a work order and photos: what goes in the email and what goes in the invoice

The job is done and the invoice is ready. Your customer wants to see a little more: the signed work order, a photo of the finished work, the quote the price is based on. Those are not decorations. With those documents a customer approves an invoice faster, and payment follows faster on an invoice that leaves nothing to ask.

This article explains where those documents belong: next to the invoice, in the same email. And how you do that in one go in SealDoc.

An invoice is a tax document

An electronic invoice under the European standard EN 16931 contains exactly what the tax authority and your customer’s accounts need: who supplies what to whom, for what amount and with which VAT. In a hybrid invoice, such as Factur-X or ZUGFeRD, that information appears twice in one file: readable in the PDF and machine-readable in the XML embedded in it.

That file goes into the records and has to stay there unchanged for years. In the Netherlands that is seven years, and ten for immovable property. Everything inside it stays in there just as long.

What EN 16931 says about attachments

The standard has a place for them: group BG-24, “Additional supporting documents”. There an invoice can refer to an external document, or carry a file as base64 inside the XML. The Peppol network allows a limited list of file types there, such as PDF, PNG, JPEG and CSV.

That it is possible does not mean you should do it. There are three reasons to keep the work order and photos next to the invoice:

1. The invoice stays clean. A photo of a gutter is not part of the tax return. Whoever checks the invoice later wants to see the invoice, not everything that happened to be inside it.
2. The invoice stays small. Base64 makes a file about a third larger. A few photos easily turn an invoice of a few hundred kilobytes into a file of several megabytes, and everyone in the chain keeps that file for years.
3. Nothing is asked of the recipient. Not every accounting package reads attachments from the XML. A PDF next to the invoice opens for everyone.

So the rule is: what the invoice needs for tax purposes goes in the invoice. What helps the customer approve it goes along in the same email.

Which documents to send along

• The work order or completion report, preferably as a PDF with the customer’s signature on it. It shows that the work was done as agreed.
• Photos of the result, for work you do on site. A few clear photos say more than a long line description.
• The quote or the order confirmation, if the invoice differs from the figure you gave earlier, or if the customer has to show internally where the price comes from.

Give each file a name that says what it is, such as work-order-2026-0142.pdf or photo-completion-1.jpg. A customer with ten attachments in their inbox then finds what they are looking for right away.

How it works in SealDoc

On an invoice’s page you find the Email invoice button. With it you do this in one go:

1. You choose the documents that go along. Those are the work orders, documents and photos you already have in SealDoc.
2. You write a personal message, if you want to tell the customer something. It can run to a few paragraphs.
3. You send. The invoice goes along as a PDF/A-3, with the XML inside, and the chosen documents as separate attachments.

Your customer sees your company name as the sender. When they click reply, their answer goes to your company’s email address shown on the invoice.

Knowing afterwards exactly what was sent

A customer who says three months later that they never received the work order, or received a different version: that is a conversation you would rather keep short. With every send, SealDoc records which documents went along, and for each document the fingerprint (the SHA-256 hash) of exactly the bytes that went out. So later you can show which version of the work order went with which invoice.

Invoice email only leaves from an account with a confirmed email address. Every send can therefore be traced back to the account that sent it.

In short

• The invoice contains what is needed for tax purposes, and nothing more.
• Work order, photos and quote go along in the same email, as separate attachments.
• In SealDoc you choose the documents for the invoice, write a message and send everything in one go, and what went along stays on record.

Want to know what else belongs in a correct invoice? Read the EN 16931 data model and why PDF/A-3 is the format of the hybrid invoice. Or start right away with invoicing in SealDoc.