The Court of Justice of the European Union (CJEU), issuing its preliminary ruling on 3 October 2019 in the Dziubak case (C-260/18), significantly influenced court case law on loans indexed to and denominated in foreign currencies, particularly in relation to Swiss francs. Although this ruling supplemented the Court’s existing case law, it was groundbreaking in the context of such disputes before common courts in Poland. It provided guidance to national courts across the EU on what should guide them in such cases. This led to a unification of the case law in this area, and even to a certain “automation” of the process.
The CJEU then took the view that a loan agreement containing foreign currency indexation clauses, due to the crucial importance of these contractual provisions and, on the other hand, the fact that such an agreement was concluded with a consumer, thus a weaker party, could be deemed invalid in its entirety. It recalled that Community law allows for judicial review of provisions of a consumer contract that were not individually negotiated with the consumer and may be unfair and misleading in nature. When entering into such an agreement, the borrower was unaware of the actual amount of the loan to be granted. This amount depended on the foreign exchange rate, unknown at the date of conclusion of the agreement, to which the agreement was indexed and which was to be determined by the defendant only on the date of loan disbursement. Therefore, the Court indicated that in contracts with entrepreneurs, the consumer is the weaker party, both in terms of information and negotiation power. Consequently, he cannot bear the negative consequences of a contractual provision the content of which he had no influence on and which was not understandable to him.
The cited CJEU position was supported by numerous subsequent rulings favorable to borrowers issued in disputes concerning the validity of loan agreement provisions. Consequently, this led, on the one hand, to a significant increase in the number of individuals filing legal proceedings in these types of cases. On the other hand, this encouraged borrowers who had entered into loan agreements on different terms (agreements in which the loan was subject to interest rates based on other indices or currencies) to verify the validity of the provisions of these agreements with respect to the interest rate on the loan amount. Therefore, when what appears to be a “wave” of lawsuits in so-called Swiss franc cases had already passed through the courts, the main focus was on assessing the validity of the provisions of housing loans whose interest rates were linked to the WIBOR index. Over 1,500 lawsuits challenging the validity of such agreements have already been filed with the courts.
In these cases, as in the case of Swiss franc loans, the justification for the claims is based on allegations of unlawful (if only due to their ambiguity) contractual provisions concerning the indexation of the loan interest rate to the WIBOR index. To date, in most cases, this has failed to persuade common courts to issue judgments favorable to the borrowers. However, this has not discouraged them from pursuing legal action.
It appears that this situation will now change significantly. The issue of interest rates on loans linked to the WIBOR index has been submitted to the Court of Justice of the European Union for resolution. In its judgment issued on October 12, 2026, in the PKO BP case (C-471/24), the Court ruled that the use of the aforementioned index and the bank margin in determining the interest rate on a loan cannot constitute grounds for invalidating such a contract. The WIBOR index operates within a comprehensive EU legal framework that ensures its reliability, accuracy, and prevents manipulation. Compliance with these regulations is ensured by the competent national authorities. The use of the WIBOR index in a loan agreement, which may be deemed compliant with legal requirements at the time of conclusion of the agreement, cannot therefore result in a significant imbalance in the rights and obligations of the parties, to the detriment of the consumer. Therefore, courts in consumer cases have no basis to question the correctness of loan agreement provisions in this respect.
At the same time, the CJEU emphasized in this ruling that it is crucial that banks properly, i.e., clearly and comprehensibly, inform customers about the reference index in accordance with national and EU law. The requirement for transparency in the information provided means, in this case, ensuring that the clause is grammatically understandable to the consumer and that they are able to assess the resulting economic consequences. It is also important that the key elements regarding the WIBOR calculation are readily accessible due to their publication. Therefore, the bank is not required to provide the consumer with detailed information on the construction of this reference index. The average observant and prudent consumer should understand the interest rate calculation method used in the contract in light of the available information and the information provided by the bank during the conclusion of the contract.
The above ruling constitutes a departure from the previous CJEU case law, which has consistently sided with borrowers. In practice, it may have a similar, yet opposite, impact to the Court’s earlier rulings in cases concerning loans indexed to foreign currencies. Primarily, it means that mass challenges to loan agreements based on the WIBOR index solely on the basis of its application will be impossible. The Court indicated that what matters most is not the factor or index itself, with reference to which the provisions of the loan agreement are shaped, but the accessibility and clarity of the information provided about them. This latter issue has a twofold significance. On the one hand, it refers to publicly available information that every consumer can and should familiarize themselves with and understand when deciding on a loan agreement referencing a specific index. On the other hand, it imposes on banks the obligation to provide information on the factor or index used in the loan agreement in relation to the method of determining its interest rate in a clear, legible and understandable manner, i.e. in compliance with the standards and requirements specified in the provisions of national and Community law.
The CJEU ruling under review will certainly set the course for Polish court decisions regarding WIBOR-based loans. It is likely that it will lead to the exclusion of claims challenging the binding nature of loan agreements solely on the basis of the use of this index. This issue was, in principle, decided negatively for borrowers in the Court’s ruling under review. However, this does not completely eliminate the possibility of declaring such agreements invalid. Nevertheless, the legal process for consumers—borrowers—to invalidate them will no longer be as straightforward and straightforward as in Swiss franc cases. The assessment will have to be individualized in this case. Proper compliance by the bank with its disclosure obligations will be crucial. This issue, as the CJEU ruling under review demonstrates, is becoming crucial. The actual dispute will therefore revolve around whether the bank reliably and clearly informed the borrower about the risk and the mechanism of the variable interest rate using the WIBOR index. The CJEU emphasized that a bank cannot present the index in a distorting manner. Therefore, if a consumer, upon entering into a contract, received information that downplayed the risk of changes in the amount of repayments (the possibility of a significant increase in the amount repaid), promised “stability,” or suggested that increases were unlikely, it cannot be ruled out that, despite the use of the permissible WIBOR interest rate in the loan agreement, the agreement may be deemed invalid.
The CJEU judgment issued on October 12, 2026, in Case C-471/24, does not therefore mean the “closure” of legal avenues for declaring the invalidity of loan agreements in which the WIBOR index was used. In this respect, as the Court emphasized, examining the validity of contractual provisions is entirely permissible. At the same time, the focus of the assessment has shifted from the index itself to the bank’s compliance with disclosure obligations. Therefore, somewhat differently than in the case of so-called Swiss franc disputes, before filing a lawsuit in such a case, an in-depth analysis of the scope, nature, and manner of information provided to the consumer before and at the conclusion of the agreement in which the WIBOR index was used will be necessary. This, in turn, means that we will not be dealing with a so-called wave of lawsuits that will “subside” after passing through the courts, but with a steady and rather limited influx of such cases in the courts. This will prevent common courts from being overwhelmed by these cases, which will also be important for the efficiency of proceedings in other cases. It will also allow for a more in-depth analysis of each case presented to the court.
