Recording and invoicing extra work: make sure it always lands on the invoice

Short answer. Extra work only lands on the invoice if you record it at the moment itself: a short description, a photo, a price or rate and customer approval, linked directly to the project. A verbal promise or a chat message disappears. A recorded line with approval flows automatically through to invoicing.

Extra work is the quietest margin leak in construction. The engineer is on site, the customer asks whether that one piece of pipe can be done as well, he does it and he drives on to the next job. Nobody writes anything down. Three weeks later the back office draws up the invoice based on the quote, and that extra hour plus materials simply is not on it. You delivered the work and you pay for it yourself.

Why extra work so often does not get invoiced

The problem is not unwillingness. It is in the chain. The engineer knows what he did, but that knowledge never reaches invoicing, or it arrives too late and too vaguely. A message in a group chat saying "customer also wants the outdoor tap" is not an invoiceable line. It lacks the price, it lacks the approval, and by the time someone draws up the invoice the chat is untraceable.

On top of that comes the legal side. Article 7:755 of the Dutch Civil Code obliges you to warn the customer in good time about the price increase caused by extra work, before you start on it. If you fail to do so, your right to compensation can lapse. Sending an invoice after the fact for work that is already finished is almost always rejected by the court. Verbally agreed extra work is therefore doubly vulnerable: it disappears from your records and it does not hold up in a dispute. BVD advocaten and Yspeert confirm that the vast majority of extra-work disputes arise because nothing was recorded in writing.

Process first, then the solution

Before I build anything, I look at what currently happens on the shop floor. Often the current route has grown organically: the engineer messages the supervisor, the supervisor messages planning, planning tries to remember it until the invoicing round. Three links where information evaporates.

The first question is not "which app" but "which steps can go". Those intermediate links exist because there once was no better way. If the engineer can record the extra work directly on site with the right fields, then the relaying of messages disappears entirely. That is deliberate cleanup, not cutting for the sake of cutting. What remains is a single moment of recording that covers everything.

What you need to record at the moment itself

Practice is clear about the fields that make an extra-work line complete. Sources such as Werkbriefje name the same set:

• Short description of what was asked for in addition.
• Evidence: a photo of the situation, and a note if needed.
• Price or rate: a fixed price or hours plus materials on a cost-plus basis.
• Customer approval: a signature or digital confirmation, on the spot.
• Link to the project: date, location, engineer and the right job.

Work with three statuses: flagged, approved, completed. Only at approval do you proceed. That way you immediately meet the duty to warn and you have the evidence that makes the invoice hold up.

Building the smarter solution

For some companies a standard work-order app like Werkbon.nl or a module in AFAS or Exact Online covers this just fine. If your extra work always follows the same pattern, you buy that. I am honest about that.

It becomes different the moment your situation does not fit the happy path of such a package. Think of extra work that is allocated differently per project, rates that differ per customer contract, or an approval flow in which the main contractor's client has to countersign before the extra work is valid. A standard package covers the happy flow. It does not cover your exceptions and your cost allocation.

That is where I build the solution. Concretely: a recording moment on the engineer's phone with exactly your fields and statuses, an integration that sets the approval up directly as an invoice line in your accounting package, and a dashboard that shows which extra work has been flagged, approved and invoiced. No loose photos, no chat messages you cannot find again. The total adds up because the calculation and the allocation are recorded in the system, not in someone's head.

The goal is not only time savings. It is grip. At any moment you can see how much extra work is outstanding and whether it has flowed through to an invoice. That is the difference between hoping the engineer remembered it and knowing it is on the invoice.