At this stage, the questions have not yet been formally referred to the CJEU. The District Court has first invited the parties to the national proceedings to submit written observations on the draft questions, after which it will decide whether, and in what final form, the questions will be referred.

Through the envisaged referral, the Amsterdam District Court seeks authoritative guidance on whether such combined indexation mechanisms are compatible with the EU framework on unfair contract terms in consumer contracts. The answers to these questions may have significant implications for Dutch tenancy law and prevailing market practice.  

Background

Since 2023, Dutch case law has reflected increasing uncertainty regarding the validity of rent indexation clauses in lease agreements for liberalised residential accommodation (see our ealier publication on Residential rental price indexation clauses analysis of judgements by the Amsterdam District Court publication). The discussion primarily concerns widely used Dutch standardised rent clauses (implemented by Raad voor Onroerende Zaken (ROZ), the Dutch Council for Real Estate) providing for an annual rent increase based on the consumer price index (CPI), supplemented by an additional surcharge, which in practice often amounts to a maximum of 5%. Several district courts held that such combined clauses may be unfair under the EU consumer protection framework with the potential consequence that both past and future rent increases could be set aside.

Before submitting its current preliminary questions to the CJEU, the Amsterdam District Court had already sought guidance from the Dutch Supreme Court on the validity of these indexation clauses. In its ruling of 29 November 2024 (ECLI:NL:HR:2024:1780), the Supreme Court ruled on a case of CPI + at most 3% surcharge. The Supreme Court ruled that the CPI-based indexation component and the surcharge component must be treated separately. The Supreme Court held that CPI-based indexation is permissible, and that a surcharge of up to 3% is, in principle, not unfair. According to the Supreme Court, such a surcharge is sufficiently foreseeable for tenants and may legitimately serve to compensate for cost increases above inflation as well as general value developments of the property.

Given the case at hand (CPI + max 3%), the Supreme Court did not explicitly comment on surcharge clauses up to a higher percentage than 3%, such as the often stipulated up to 5% surcharge clause. Clauses with such higher surcharge were subsequently, however, assessed in various court cases (both with district courts and courts of appeal), where often times the court questions if the surcharge clause is sufficiently transparent and the financial consequences are foreseeable for the tenant when concluding the lease agreement. The most substantive review of transparency and foreseeability of (the consequences of) the surcharge clauses took place in the judgments of the Amsterdam Court of Appeal of 2 and 9 December of 2025 (ECLI:NL:GHAMS:2025:3213 and ECLI:NL:GHAMS:2025:3360). In these cases, the Amsterdam Court of Appeal ruled that a surcharge clause of up to 5% on top of CPI indexation is unfair. According to the court, such a surcharge lacks sufficient medium- and long-term transparency for tenants, meets the characteristics of amendment clauses listed as indicative of unfairness under EU law, and materially distorts the contractual balance to the tenant’s detriment. Consequently, while CPI indexation remained applicable, the surcharge clause had to be disapplied, both retrospectively and going forward. Various lower courts and other courts of appeal have arrived at similar outcomes as the Amsterdam Court of Appeal.

Preliminary draft questions

Against this background, the Amsterdam District Court has, in its ruling, set out the draft preliminary questions it intends to put to the CJEU regarding the compatibility of rent indexation and surcharge clauses with European consumer protection law (ECLI:NL:RBAMS:2026:4166). Through these preliminary questions, the District Court aims to obtain guidance on the proper assessment of such clauses, and in particular on the permissibility, under EU law, of combining CPI indexation with an additional surcharge.

Question 1

Does EU law preclude the severance of a single rent rent‑adjustment clause into two separate clauses, where such a clause contains both (i) a price indexation clause and (ii) a second surcharge mechanism allowing for an increase of the (rent) price? If such severance is permissible, should those terms be assessed separately for fairness, in the sense that, if one term is found to be unfair, the other term, namely the indexation clause, may remain in force?

Question 2

If such severance of clauses is permissible, should the cumulative effect of both clauses be examined, and should both clauses be disapplied where their combined effect is such that it must be concluded that the balance of rights and obligations arising under the lease agreement is significantly distorted to the detriment of the consumer (i.e. the tenant)?

Question 3

Is the Dutch Supreme Court’s assessment, in its ruling of 29 November 2024, that a rent‑adjustment clause is not unfair, compatible with EU law:

  1. Where the clause itself does not specify the grounds on which the price may be adjusted, but the trader (i.e. the landlord) subsequently puts forward reasons for the price increase after the conclusion of the contract? In that context, does it matter whether the reasons advanced are plausible? Can a maximum supplement, determined by reference to the value of the dwelling, be regarded as a sufficiently clear method of price adjustment, and does an increase in the value of a dwelling constitute a sufficiently valid ground for increasing the rent?
  2. If the clause can only lead to a rent increase and not to a rent decrease?
  3. Where termination of the lease agreement is legally possible, but termination is, in practice, not a genuinely effective option for the tenant as a result of the prevailing conditions on the Dutch housing market?
Question 4

Is the fairness of a rent‑adjustment clause affected by the fact that the clause provides that the adjusted rent applies even if the tenant has not been individually notified of the adjustment, as is the case in the rent‑adjustment clause at issue?

Question 5

To what extent, when assessing the fairness of a surcharge clause, should account be taken of the maximum foreseeable rent increase at the time the contract is concluded, in relation to the then foreseeable potential increase or decrease of the income of the individual tenant, and that tenant’s ability to continue paying the increased rent? In other words, to what extent should individual circumstances be taken into account in that assessment, for example where a tenant receives a statutory old‑age pension (Dutch acronym: AOW) and a decline, rather than an increase, in real income can reasonably be expected?

Question 6

Does the exception referred to in point 2(d) of the Annex to Directive 93/13 preclude a (otherwise lawful) price-indexation clause that merely refers to a percentage annually published by an independent national authority, without explicitly describing in the clause the method by which the price is adjusted, where the consumer (i.e., the tenant) is nevertheless generally familiar with that index?

What is next?

At this stage, the preliminary questions have not yet been formally referred to the CJEU. In its ruling, the Amsterdam District Court has first invited the parties to the national proceedings to submit written observations on the draft questions by 26 May 2026. Only after this exchange will the District Court decide whether, and in what final form, the questions will be referred to the CJEU.

Once the District Court of Amsterdam submits its request for a preliminary ruling, the CJEU will formally open the procedure. The CJEU will then invite the parties to the national proceedings, the EU Member States, the European Commission, and – if relevant – EU institutions to submit written observations on the referred questions. After the written phase, the CJEU may decide to hold an oral hearing, during which parties and intervening Member States can present their views and respond to questions from the judges.

Following these stages, the Attorney General will normally issue an opinion, after which the CJEU will deliver its judgment. The average duration of a preliminary ruling procedure is 16 to 24 months, unless the CJEU grants an expedited or simplified procedure, in which case the timelines can be reduced significantly. Once the judgment is issued, the referring Dutch court must apply the interpretation provided by the CJEU when deciding the national case, and that interpretation is also authoritative for other national courts applying the same EU provisions.

The CJEU’s judgment could have various implications for ongoing and future litigation. For tenants, this may include the possibility of individual or class actions challenging indexation clauses, particularly where similar clauses appear across large numbers of lease agreements. For landlords and investors, potential consequences may involve reassessing the enforceability of certain rent-increase mechanisms, including the possibility that specific clauses may be considered voidable or inapplicable, which in some instances could give rise to claims for repayment of past increases.

Get in touch

Our combined team of real estate and litigation experts will monitor the developments closely. If you have questions about the issues discussed above or would like to explore how these developments may affect your portfolio or leasing practices, please contact one of our team members listed below.