Disputed invoice in Belgium: what if your client protests?

You send a reminder and the reply is that the invoice is “disputed”. Or the other way round: you receive an invoice for work that was not carried out, or was carried out poorly. With a disputed invoice in Belgium, everything turns on one question: what does an invoice prove, and how and when should you dispute an invoice?

A protest is not automatically a valid dispute, and its timing often carries more weight than its content. This article explains how the rules work under Belgian law, for businesses and for consumers alike.

The evidential value of an accepted invoice between businesses

Since 1 November 2020, Article 8.11 of the Civil Code (Burgerlijk Wetboek / Code civil) has provided that, unless proven otherwise, an invoice accepted by a business (onderneming / entreprise) or not disputed by it within a reasonable time constitutes evidence against that business of the legal transaction claimed. This rule applies to all contracts, not only to sales, as was the case under the former Commercial Code. An invoice can be accepted expressly, but also tacitly.

Acceptance is not absolute proof. The business that received the invoice can still prove the contrary, but it needs serious evidence to do so. If you do not protest in time, you therefore start at a disadvantage.

An invoice addressed to a consumer

The rule in Article 8.11 applies only against businesses. Against a consumer, an undisputed invoice carries far less evidential weight, because an invoice is first and foremost a document the business draws up itself. The business must prove the existence and content of the contract in another way, for example with a signed quotation, an order form or emails.

Where the amount is EUR 3,500 or more, Article 8.9 of the Civil Code in principle requires a signed document to prove the contract; below that amount, all forms of evidence are admissible. As a consumer, you are nevertheless well advised to dispute an invoice you disagree with promptly and in writing.

Debt collection from consumers is also governed by the rules of Book XIX of the Code of Economic Law (Wetboek van economisch recht / Code de droit économique). The first reminder is free of charge, after which the consumer has fourteen calendar days to pay before the business may charge any compensation for late payment.

How long do you have to dispute an invoice?

The law does not set a fixed deadline. What is reasonable depends on the nature of the service, the time needed to check it, the practices of the sector and the relationship between the parties.

A dispute about whether an order was placed at all should come quickly; for complex works, a longer inspection period may be acceptable. In practice, courts have little sympathy for a protest that surfaces months later, especially when it appears for the first time after a payment reminder.

If you pay without reservation, pay in part or start using the goods without comment, you weaken any later dispute. Entering the invoice in your accounts or deducting the VAT shown on it may also be seen as an indication of acceptance.

How to dispute an invoice properly: five rules

1. In writing, with proof of sending and receipt: registered mail, or an email whose receipt you can prove.
2. Reasoned and precise: which part of the invoice are you disputing, and why? A general statement that you disagree is not enough.
3. Promptly: the longer you wait, the weaker your position.
4. With evidence: photos, reports, emails and, in larger disputes, an official report by a bailiff (gerechtsdeurwaarder / huissier de justice) or an expert’s report.
5. Pay the undisputed part: this shows your good faith and limits interest and costs.

An example of a proper protest

“We acknowledge receipt of your invoice no. 2026/145 of 3 March 2026. We dispute it in the amount of EUR 1,250, because the delivery of 20 February 2026 was incomplete: five of the twelve panels ordered were missing, as noted on the delivery note and as shown in the attached photos. We will pay the undisputed balance of EUR 3,750 within the payment term. We reserve all our rights.”

A protest like this is specific, dated, substantiated and limited to what is genuinely in dispute. To a judge, it is far more convincing than a general refusal to pay.

Withholding payment: the exception of non-performance

If the other party fails to perform its obligation, or performs it poorly, you may as a rule suspend your own performance, for example payment of the disputed part. For contracts concluded on or after 1 January 2023, this exception of non-performance (exceptie van niet-uitvoering / exception d’inexécution) is laid down in Article 5.239 of the Civil Code; for older contracts, the courts already recognised the same principle.

The suspension must be exercised in good faith and in proportion to the breach. Blocking an entire invoice over a minor defect is risky: you may yourself be regarded as the party in breach. Have the proportionality assessed beforehand.

Terms and conditions printed on the invoice

Many invoices refer to general terms and conditions, including a penalty clause (schadebeding / clause pénale), an interest clause or a jurisdiction clause. As a rule, those terms only bind the client if the client was aware of them and accepted them, normally before or at the time the contract was concluded.

Terms that appear for the first time on the invoice are therefore on weaker ground, although a long-standing business relationship between companies may lead a court to take a different view. So have your general terms and conditions accepted at the quotation or order stage. See also which late-payment interest and penalty clause you can claim when a client pays late.

What does a disputed invoice mean for debt recovery?

This is the pivotal point. The IOS procedure for uncontested debts (invordering van onbetwiste schulden / recouvrement de dettes non contestées), which allows monetary debts between businesses to be recovered through a bailiff and without going to court, is only available for undisputed debts. If the debtor disputes the claim, that route is closed and the creditor has to go to court.

That is why some debtors raise a dispute purely for form’s sake: they are buying time. A lawyer can assess whether a protest is genuinely serious or merely a delaying tactic, and which procedure will then lead to payment most quickly. More about the IOS procedure.

If the protest turns out to be unfounded, proceedings before the competent court follow; the full process is explained in our article on recovering unpaid invoices.

Frequently asked questions

My client only protested after three months. Does that still count?

That depends on the circumstances. Between businesses, such a long silence generally points towards acceptance, with the evidential force of Article 8.11 as a result. It may be different if the client shows that the defect could only be discovered later.

Does an invoice have to be disputed within eight days?

No, the law does not provide for a fixed eight-day deadline. Such a deadline only applies if it was agreed between the parties, for example in accepted general terms and conditions. Otherwise a reasonable time applies, and even then a quick response is the best protection.

My client disputes only part of the invoice.

The undisputed part then generally remains payable. You can recover that part separately and argue or litigate only over the disputed balance.

Does a dispute stop the limitation period on my invoice?

No. A protest by your client does not interrupt the limitation period (verjaring / prescription) for the disputed amount. Which period applies is explained in our article on the limitation period for invoices. So do not wait too long before taking further steps.

I am a consumer and received an invoice I never accepted.

Dispute it in writing, with reasons and without delay, and ask the business for proof of the contract. Do not pay under pressure from a payment reminder without having the basis of the claim checked.

Disputed invoice? Novex Advocaten can help

Is your invoice being disputed, or are you disputing one yourself? We assess how serious the protest is, draft a proper dispute letter or formal notice (ingebrekestelling / mise en demeure), and choose the quickest route to a solution.

Call 0484 99 22 72 or email asfour@novexadvocaten.be.