WIBOR litigation: Court of Justice ruling in C-471/24, J.J. v PKO BP SA | In Principle

We recently reported on the growing number of lawsuits against banks by consumers challenging clauses in credit agreements based on the WIBOR benchmark, alleging that they are “unfair” under Directive 93/13/EEC. Both lenders and borrowers anxiously awaited a decision by the Court of Justice in C-471/24, J.J. v PKO BP SA, on a request for a preliminary ruling submitted by the Częstochowa Regional Court. The judgment handed down on 12 February 2026 clearly met the expectations of the banking sector more than borrowers.

The ruling undoubtedly sets out a new line of case law in disputes over loans tied to the WIBOR benchmark, although it was already evident that borrowers would not have such a simple or schematic path to setting aside such agreements as borrowers had in challenging agreements for credit denominated in Swiss francs. Merely tying the interest rate to WIBOR (the Warsaw Interbank Offered Rate) is not enough to render the clause “unfair.” The crucial question is whether the bank properly performed its informational obligations, and that can be assessed only on a case-by-case basis.

Below we discuss the main conclusions from the responses given by the Court of Justice to each of the questions referred by the Polish court.

First question: contract terms reflecting mandatory provisions of law

In the first question, the Polish court sought to determine whether Art. 1(2) of Council Directive 93/13/EEC of 5 April 1993 on unfair terms in consumer contracts excludes the possibility of examining the fairness of contractual clauses employing the WIBOR benchmark as the basis for determining variable interest rates. That section states that “contractual terms which reflect mandatory statutory or regulatory provisions … shall not be subject to the provisions of this Directive.” If so, such clauses could not be reviewed for their alleged unfairness to consumer borrowers.

The doubts on the part of the Polish court arose under Art. 29(2) of Poland’s Mortgage Credit Act, which provides, “If the parties have not agreed on a fixed mortgage interest rate, the method for determining the interest rate … shall be taken to mean the benchmark figure and the amount of the margin stipulated in the mortgage loan agreement.” The dispute before the court in Częstochowa involved mortgage credit.

However, the Court of Justice stressed that the exclusion in Art. 1(2) of Directive 93/13/EEC should be strictly construed. The exclusion “does not apply in a situation where legislation merely establishes a general framework for setting the interest rate applicable to such agreements, while leaving the seller or supplier a margin of discretion as regards both the choice of the reference index for that rate and the size of the fixed margin that can be added to that rate.”

Consequently, the Court of Justice held that Art. 29(2) of the Mortgage Credit Act was too general to serve as a basis for excluding the application of Directive 93/13/EEC to mortgage credit agreements using WIBOR as the basis for setting variable interest rates.

Second question: interest rates as the main subject matter of the contract, and the requirement of transparency

The second question referred by the Polish court concerned whether the contractual provisions adopting WIBOR as the basis for variable interest rates constitute the “main subject matter of the contract” for purposes of Art. 4(2) of Directive 93/13/EEC, and what conditions must be met to regard these provisions as expressed in “plain, intelligible language,” i.e. satisfying the requirement of transparency.

Under Art. 4(2), assessment of the fairness of terms must not relate to “the definition of the main subject matter of the contract,” as long as “these terms are in plain intelligible language.” In this respect, the Court of Justice recognised that a provision determining the interest rate in a credit agreement may constitute the main subject matter of the contract. In that case, the unfairness of such a provision may be examined only if does not satisfy the requirement of transparency.

The Polish court wondered whether to meet the requirement of transparency, the bank must inform the borrower in detail of the methodology for calculating the WIBOR benchmark.

The Court of Justice pointed out that WIBOR 6M, the reference rate which was the subject of the dispute in the proceeding before the referring court, is subject to the Benchmark Regulation ((EU) 2016/1011), which imposes informational obligations involving the methodology behind the benchmark primarily on the administrator of the benchmark. Thus there is a division of informational obligations between the banks and the benchmark administrator. It is the task of the bank granting mortgage credit to provide consumers with information enabling them to:

• Assess the actual consequences of the variability of the interest rate on their obligations, in accordance with the requirements of the Mortgage Credit Directive (2014/17/EU), and
• Acquaint themselves with all the information that the administrator of a benchmark must make public.

Thus, to meet the requirement of transparency, it is not necessary for the banks to present to consumers the detailed methodology for setting the WIBOR. However, if they do decide to describe the methodology, the information must be accurate and consistent with the information published by the benchmark administrator. Once the bank meets the requirement of transparency, the court will not move to an examination of the fairness of the contract term introducing the WIBOR, because it is part of the main subject matter of the contract.

Third question: unfairness of contractual provisions introducing variable interest rates based on WIBOR

In the third question referred, the Polish court sought to determine whether, if the transparency requirement were not met, the provision of the credit agreement concerning variable interest based on WIBOR may be regarded as unfair under Art. 3(1) of Directive 93/13/EEC.

These doubts particularly involved whether the assessment of unfairness was impacted by the failure to inform the consumer that:

• The methodology for calculating the benchmark may use input which does not necessarily correspond to actual transactions, and
• The lender is one of the banks contributing to determination of the index.

The court also wondered whether these aspects of the benchmark could in themselves render the provision unfair.

In this respect, the Court of Justice stressed that the WIBOR 6M under consideration in the case is a benchmark governed by the BMR, which covers both development and application of the benchmark. Compliance with these requirements is ensured by a system of prior control and supervision exercised mainly by the competent national authorities. The Court of Justice further indicated that no contributing bank is in a position by itself to exercise a decisive influence over the value of an interest rate benchmark. Consequently, it held that the use of a benchmark complying with the requirements of the BMR cannot in itself render the contractual provision unfair—even if the lender is one of the banks contributing input data for establishing the benchmark. In that case, apart from its informational obligations under Directive 2014/17/EU, the bank has no obligation to inform the consumer that the benchmark may be determined on the basis of offers rather than actual transactions, or that the lender itself is one of the banks contributing input data used to set the benchmark.

The Court of Justice confirmed that to assess the overall fairness of contractual terms adopting WIBOR as the basis for variable interest rates, the method of calculating interest provided in the agreement should be compared to the nature and level of interest rates generally observed on the Polish market, as well as the rates of statutory interest and market rates in force at the time the agreement was made. This means that the relevant circumstances which the national court should consider when assessing the fairness of the challenged contractual provision include:

• The level of interest rates commonly applied on the Polish mortgage credit market, and
• The level of the WIBOR compared to other similar indicators at the time of conclusion of the credit agreement.

Summary

In C-471/24, J.J. v PKO BP SA, the Court of Justice held that the mere use of WIBOR as a benchmark within the meaning of the Benchmark Regulation does not determine the unfairness of a contractual provision. However, it remains an open question whether the same conclusions apply to WIBOR from the period before it was covered by the BMR regime—an issue that will probably be resolved in further rulings by the Court of Justice.

In this case, the court held that what is of crucial importance is lenders’ compliance with their informational obligations. In the case of mortgage credit, meeting the requirement of transparency is linked with the lender’s compliance with the Mortgage Credit Directive.

At the same time, the Court of Justice expressly stated that the bank is not obliged to provide detailed information on the method of calculating a benchmark within the meaning of the BMR—this duty rests with the administrator of the benchmark. This is undoubtedly a very advantageous ruling for the banking sector, as this was one of the main arguments raised by borrowers in WIBOR disputes.

Mateusz Kosiorowski, adwokat, Anna Szczęsna, Dispute Resolution & Arbitration practice, Wardyński & Partners