Late payment interest and penalty clauses in Belgium: what can you claim?

A customer who pays late costs you money. Between businesses, the Belgian Act of 2 August 2002 on combating late payment in commercial transactions (wet betreffende de bestrijding van de betalingsachterstand bij handelstransacties / loi concernant la lutte contre le retard de paiement dans les transactions commerciales) gives creditors strong tools: late payment interest that accrues by operation of law, a fixed compensation of €40 and a statutory cap on payment terms. Many businesses do not use them, or use them incorrectly. This article explains what late payment interest and costs you can claim in Belgium, when a contractual penalty clause will hold up and which different rules apply to consumers.

When does the Late Payment Act apply?

The Act applies to payments made as remuneration for commercial transactions: supplies of goods or services between businesses, or between businesses and public authorities. It does not apply to consumers; for them, the mandatory rules of Book XIX of the Code of Economic Law (Wetboek van economisch recht / Code de droit économique) apply.

The payment term between businesses

Unless otherwise agreed, an invoice between businesses must be paid within thirty calendar days of receipt of the invoice or of the goods or services. The parties may agree on a different term, but since 1 February 2022 a contractual payment term between businesses may not exceed sixty calendar days.

A clause providing for a longer term is deemed unwritten (voor niet geschreven gehouden / réputée non écrite), even in general terms and conditions. Where the law or the contract provides for an acceptance or verification procedure, the time taken for that verification forms an integral part of the payment term.

Late payment interest in Belgium: automatic and without formal notice

If payment is not made on time, the creditor is entitled by operation of law, and without formal notice, to late payment interest from the day after the due date. This is an essential difference from the ordinary civil-law rules, under which interest generally only starts to run after a formal notice of default (ingebrekestelling / mise en demeure).

Which interest rate applies?

The rate consists of the European Central Bank’s reference rate, increased by eight percentage points and rounded up to the next half percentage point (Article 5 of the Act). It is published every half-year by the Federal Public Service Finance in the Belgian Official Gazette (Belgisch Staatsblad / Moniteur belge). For both the first and the second half of 2026, it stands at 10.5%.

Because the rate can change from one half-year to the next, we always calculate interest at the rate applicable to the period concerned. For arrears that are still outstanding, we check the most recent notice in the Belgian Official Gazette.

A worked example

An invoice of €10,000 due on 1 February 2026 is only paid on 2 April 2026, sixty days late. At 10.5% per year, the interest amounts to 10,000 × 10.5% × 60/365, or €172.60 rounded. The fixed compensation of €40 comes on top of that.

For a business that is structurally paid late, these amounts add up quickly. The Act allows you to claim them without any further formality.

The fixed compensation of €40 and recovery costs

In addition to interest, the creditor is entitled by operation of law to a fixed compensation of €40 for its recovery costs. If the actual recovery costs exceed that amount, the creditor may claim reasonable compensation for the difference, provided those costs are proven. For legal fees in court proceedings, the procedural indemnity applies in principle (see below).

The contractual penalty clause

Many general terms and conditions include a penalty clause (schadebeding / clause pénale), often a percentage of the invoice amount with a minimum, together with contractual interest. Between businesses this is permitted in principle, but not without limits.

For contracts concluded since 1 January 2023, the court reduces a penalty clause that is manifestly unreasonable, of its own motion or at the debtor’s request, taking into account the loss and all other circumstances (Article 5.88, § 2, of the Civil Code). Under the old law, too, the court could moderate an excessive clause (Article 1231 of the old Civil Code).

Two practical points:

• your general terms and conditions only apply if your customer knew and accepted them, as a rule before or at the time the contract was concluded; terms that appear for the first time on the invoice are in a weaker position (see drafting general terms and conditions);
• the penalty clause and the statutory fixed compensation do not necessarily compensate the same loss; have your file checked to see what you can combine.

Outside commercial transactions: statutory interest

If the Late Payment Act does not apply and no contractual interest has been agreed, the creditor of a sum of money can as a rule claim statutory interest (wettelijke interest / intérêt légal) from the date of the formal notice. The statutory interest rate in civil matters is set every year and published in the Belgian Official Gazette, and it is considerably lower than the rate between businesses. More on the formal notice of default.

Consumers: the rules of Book XIX

If your customer is a consumer, you may not apply the business-to-business regime. The first reminder must be free of charge and the consumer then has at least fourteen calendar days to pay. Only once that period has expired may interest and fixed damages be charged.

These amounts are capped by law. Fixed damages may not exceed €20 for an amount up to €150 and rise in bands to an absolute maximum of €2,000; late payment interest may not exceed the reference rate plus eight percentage points. A penalty clause providing for any other amounts is prohibited and deemed unwritten (Article XIX.4 of the Code of Economic Law). More on Book XIX.

In court

If the matter goes to court, the judge will as a rule also order the losing party to pay the legal costs, including a procedural indemnity (rechtsplegingsvergoeding / indemnité de procédure): a fixed contribution towards the winning party’s legal fees. For undisputed invoices between businesses, there is also a faster route without going to court: the IOS procedure for undisputed debts. You will find the full process in our article on recovering unpaid invoices.

Practical tips for creditors

1. State the payment term, the interest and the penalty clause clearly on your quotes and invoices, and make sure your general terms and conditions are accepted in advance.
2. Monitor due dates and send a reminder in good time.
3. Calculate interest per half-year at the correct rate.
4. Respond quickly and in writing if your customer disputes the invoice, and keep proof of delivery or performance (see disputed invoices).
5. Do not wait too long: limitation periods and your customer’s solvency work against you.

Frequently asked questions

Do I have to send a reminder before interest starts to run?

Not in a commercial transaction: late payment interest runs by operation of law from the day after the due date. With a consumer, the formalities of Book XIX do apply, starting with a free first reminder.

My general terms and conditions provide for a 15% penalty clause. Is that valid?

Between businesses it can be, but the court will reduce the clause if it is manifestly unreasonable, taking into account the loss and all other circumstances. With a consumer, the statutory scale of Book XIX applies; for larger amounts, a fixed percentage of 15% will generally exceed it.

Does the Act also apply when my customer is a public authority?

Yes, the Act also applies to commercial transactions between businesses and public authorities. Public procurement contracts are also subject to specific rules on payment terms. Have these checked for your file.

Can I recover my legal fees?

Partly. In court proceedings you receive the procedural indemnity as a fixed contribution. Between businesses, you can also claim reasonable compensation for proven recovery costs above the fixed €40.

What if my customer is declared bankrupt?

You can then no longer pursue individual recovery. You file your claim with the bankruptcy trustee (curator / curateur) through the central register Regsol, within the period set in the bankruptcy judgment. How to file your claim.

Novex Advocaten can help

We calculate what you can actually claim in late payment interest, fixed compensation and penalty clauses, we draft or adapt your general terms and conditions, and we handle debt recovery from start to finish.

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