How to Document and Invoice Change Orders in Belgian Construction

Practical guidance for Belgian construction SMEs on creating, approving, and invoicing change orders to avoid disputes and ensure proper record‑keeping.

Enfin editorial teamUpdated: 5 minute read

What is a change order?

A change order (Dutch “meerwerkbon”) records work that was not included in the original quotation. When the client accepts the change order—preferably in writing—it becomes a supplemental agreement to the main contract. A signed document, whether paper‑based or digital, provides the most reliable proof of agreement.

Core elements of a valid change order

ElementWhat to include
Clear descriptionDetail the extra work (e.g., “relocate drainage pipe from point A to point B and seal the existing opening in the floor slab”).
PriceState the amount exclusive of VAT and indicate the applicable VAT rate. If the scope is uncertain, add a note such as “estimate based on actual costs”.
DateRecord the day the change order is created.
Client signatureObtain a signature (digital or handwritten). Keep a copy of the signed document.

Typical on‑site workflow

  1. Identify the issue – The foreman notices a deviation from the original plan and informs the office.
  2. Prepare the change order – The office drafts the document, attaches any relevant photos, and includes the price and VAT information.
  3. Send for approval – The change order is sent to the client by e‑mail or through a client portal.
  4. Capture the signature – The client signs digitally, or the foreman records a handwritten signature on a tablet after photographing the problem.
  5. Store the document – Save the signed change order in the project’s electronic folder for future reference.

If you use a project‑management tool that supports change orders, you can attach photos, descriptions and prices directly to the project file. Once the client approves, the item can be turned into a billable line in your invoicing system.

When to request written approval

Belgian law does not set a specific threshold for extra work, but written approval is the safest way to avoid later disputes. As a practical rule, obtain written consent before starting any work that adds a separate cost to the contract. Even for small amounts, keep a written record (e‑mail, signed note, or digital form) to demonstrate that the client was informed.

Legal and tax considerations

  • Contractual evidence – A signed change order is treated as an amendment to the original contract. It should be referenced in any subsequent invoice.
  • VAT – Include the VAT amount on the invoice in accordance with the Belgian VAT rules. Verify the correct rate for the specific work on the VAT information page of the Federal Public Service Finance.
  • E‑invoicing – Since 1 January 2026, Belgian B2B e‑invoicing is mandatory. Ensure that your final invoice, including the change‑order line, complies with the requirements described on the official e‑invoicing portal.

Common pitfalls and how to avoid them

PitfallWhy it mattersPrevention
Adding the extra cost only on the final invoiceThe client may see an unexpected increase and dispute payment.Issue a signed change order before the work begins and reference it on the invoice.
No visual evidence of the issueYou lack proof that the extra work was necessary.Take a photo as soon as the problem is identified and attach it to the change order.
Relying on oral agreementsVerbal statements are difficult to verify later.Use a written or digitally signed document; keep any confirming e‑mail as backup.

Handling a client who refuses to sign

If a client declines to sign the change order, you have two practical options:

  1. Do not perform the extra work – Document the refusal (e‑mail) and the issue with photos. Continue with the rest of the project. This protects you from later claims that the work was ignored.
  2. Proceed with caution – Carry out the work, keep thorough documentation (photos, timestamps, daily logs), and be prepared for a possible non‑payment. This approach is only advisable when the extra work is essential to complete the main contract (e.g., replacing a load‑bearing beam before the wall can be closed).

To reduce the likelihood of refusal, include a clause in your original quotation such as: “Unforeseen works will be discussed in advance and quoted separately. No extra work will be carried out without written client approval.”

Digital signatures and security

Belgian regulations recognise qualified electronic signatures as equivalent to handwritten signatures. When using a digital signature solution, ensure that:

  • The provider complies with the eIDAS regulation.
  • The signature is linked to the signatory’s identity and the signed document cannot be altered after signing.

Storing the signed PDF in a secure, backed‑up location satisfies both contractual and audit requirements.

Record‑keeping checklist for every change order

  • Write a precise description of the extra work.
  • Attach a photo of the issue (if applicable).
  • State the price exclusive of VAT and indicate the VAT rate.
  • Record the date of creation.
  • Obtain the client’s signature (digital or paper).
  • Save the signed document in the project folder or management system.
  • Reference the change order number on the subsequent invoice.

Following this routine adds only a few minutes to your daily process but creates a clear audit trail that can prevent costly disputes.

Further assistance

For general questions about change‑order management or to discuss how your existing tools can support the workflow described above, please contact us through the Enfin contact page.

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