Contractual interest and collection costs tested against reasonableness and fairness
Supreme Court: the court of appeal should have assessed the defence on excessive interest and costs
Acknowledge Benelux B.V. procured cloud services from Interconnect Services B.V. The dispute centred on excess use of 'powered-on memory': Interconnect claimed just over €514,000. The court of appeal largely allowed the claim — including 1.5% interest per month and €63,000 in collection costs. The Supreme Court partially reverses that decision.
Interconnect claimed the interest under Article 19.8 of its general terms and conditions and the collection costs under Article 19.9 (15% of the principal sum). The district court had dismissed the claim. On appeal, the court of appeal held that the general terms and conditions applied and awarded €494,462.39, plus the contractual interest and the collection costs. Acknowledge brought an appeal in cassation.
Before the courts on the facts, Acknowledge had expressly invoked Section 6:248(2) DCC: the derogating effect of reasonableness and fairness. That plea entails that the application of a contractual provision is, in the given circumstances, unacceptable by the standards of reasonableness and fairness. The court of appeal had not assessed that defence.
A valid clause may still operate unacceptably
On the contractual interest of 1.5% per month — equivalent to 18% on an annual basis — the Supreme Court holds that the court of appeal did not adequately address Acknowledge's defence. Acknowledge had specifically argued that this interest rate is excessively high. The court of appeal confined itself to establishing that the general terms and conditions applied, but did not address the question whether the application of this rate is unacceptable in the circumstances of the case. That is a failure to state adequate reasons.
The same applies to the collection costs. The court of appeal held that Acknowledge had put forward insufficient grounds for the conclusion that Article 19.9 is invalid. But the Supreme Court corrects that reasoning: a defence under Section 6:248(2) DCC precisely presupposes that the clause is valid. The defence is not about validity, but about the unacceptability of its application in the specific case. Acknowledge had specifically pointed to the disproportion between the amount claimed and the actual collection efforts. The court of appeal should have assessed that defence on its merits. Because it did not, the judgment is, on this point, insufficiently reasoned. The case is referred to the Court of Appeal Arnhem-Leeuwarden.
What does this mean for parties faced with high contractual costs?
A party faced with contractual interest or cost clauses that bear no relation to the actual loss or effort has an independent defence under Section 6:248(2) DCC. That defence is separate from the question whether the clause is voidable. Even where the general terms and conditions apply in full, the court may consider the application of a specific clause unacceptable in the circumstances of the case. This does, however, require a concretely substantiated argument: what amount is set against what performance, and why is that relationship unacceptable?
This judgment is relevant to any party faced, in a commercial dispute, with high contractual interest or collection costs based on general terms and conditions. A court that merely passes over such a defence by stating that the terms apply gives inadequate reasons. That provides grounds for cassation. More on the operation of general terms and conditions and proportionality defences in commercial contracts can be found in the publications.
Frequently asked questions
What is the derogating effect of reasonableness and fairness?
Section 6:248(2) DCC provides that a contractual rule does not apply to the extent that this would, in the given circumstances, be unacceptable by the standards of reasonableness and fairness. It concerns not the validity of the clause, but the unacceptability of its application in a specific case. The threshold is high, but where interest or costs are extremely high the defence has a real prospect of success.
Can a valid general term still be disapplied?
Yes. In this judgment the Supreme Court confirms that a plea under Section 6:248(2) DCC presupposes that the clause is valid. Precisely because the clause is valid, the court must separately assess whether its application is unacceptable in the concrete circumstances. Validity and applicability are two distinct questions.
What must you specifically put forward for this defence to succeed?
Put the disproportion at the centre: what amount is claimed under the clause, what the actual costs or loss were, and why that discrepancy is unacceptable. Abstract assertions are not enough. In this case Acknowledge specifically pointed to the relationship between the collection costs claimed and Interconnect's actual collection efforts.
ECLI:NL:HR:2026:348, Supreme Court, 6 March 2026
Cited case law
Supreme Court: ECLI:NL:HR:2026:348