Many zloty loans, especially mortgages, have a variable interest rate based on the WIBOR benchmark. In practice, the interest rate on such a loan usually consists of the WIBOR rate and the bank’s margin, so changes in interest rates can directly affect the amount of the instalment and the total cost of the loan.

However, rising instalments do not in themselves mean that the agreement was concluded improperly. WIBOR cases above all require an analysis of the wording of the specific agreement, the way the variable interest rate was set out and the information given to the borrower before signing.

Our firm helps borrowers analyse loan agreements based on WIBOR and assess whether there are grounds for bringing specific claims against the bank.

How we can help

In cases concerning WIBOR loans, our work includes, among other things:

• analysing the loan agreement and terms and conditions,

• assessing the variable interest rate provisions,

• analysing the information given to the borrower before signing the agreement,

• assessing how the interest rate risk was presented,

• analysing documentation concerning the WIBOR benchmark,

• identifying possible grounds for claims against the bank,

• preparing complaints and demands to the bank,

• analysing settlement proposals and annexes,

• representing the borrower in court proceedings.

Every agreement requires an individual assessment. We do not assume in advance that the mere use of WIBOR in an agreement gives grounds to challenge it.

What is WIBOR?

WIBOR is an interest rate benchmark that for many years was widely used to set the interest rate on zloty loans.

Loan agreements used, among others, WIBOR 3M and WIBOR 6M. The value of the benchmark was updated periodically, and the interest rate on the loan and the amount of subsequent instalments changed with it.

For the borrower, what matters is therefore not only which benchmark was written into the agreement, but also whether the way the interest rate was set was presented clearly and whether the consumer received information allowing them to understand the economic consequences of a variable interest rate.

Can an agreement with WIBOR be challenged?

The use of WIBOR alone does not automatically mean that a contractual provision is unfair or that the entire loan agreement is invalid.

Current case law indicates that in cases of this kind, what may be particularly important is primarily the transparency of the agreement and the scope of information given to the borrower.

The analysis may cover, among other things:

• how the agreement defined the variable interest rate,

• whether the borrower knew what its level depended on,

• whether they were informed of the consequences of a rise in interest rates,

• what information about the benchmark was available when the agreement was signed,

• whether the provisions of the agreement allowed the consumer to assess the potential impact of interest rate changes on their obligation.

Solutions known from Swiss franc cases therefore cannot be transferred directly to zloty loans based on WIBOR.

WIBOR after the 2026 CJEU judgment

In February 2026, the Court of Justice of the European Union ruled in a Polish case concerning a loan based on WIBOR.

The Court did not find that the use of WIBOR alone makes a contractual term unfair. Nor did it hold that the bank is obliged to present to the consumer the entire methodology for calculating the benchmark in detail.

However, the way the agreement was worded and whether the bank properly fulfilled its disclosure obligations towards the borrower may still be relevant.

That is why, after this judgment, WIBOR cases require an even more individual approach. There is no single pattern that would allow us to say that every loan based on WIBOR can be successfully challenged.

Variable interest rate risk

A WIBOR loan linked the interest rate to the value of a benchmark that could change throughout the term of the agreement.

With a mortgage taken out for 15 or 30 years, even a significant change in the level of interest rates could have a major impact on the amount of instalments.

That is why, when analysing the agreement, we also look at how the bank informed the client about the risk of interest rate changes and the possible financial consequences of such a change.

The mere information that the interest rate is “variable” does not always give a full picture of the risk. The final assessment, however, depends on the content of all the documentation and the circumstances in which the agreement was signed.

WIBOR and POLSTR

The market for benchmarks in Poland is currently undergoing changes. In new products, WIBOR is gradually being replaced by the POLSTR benchmark.

This change does not, however, automatically mean that earlier agreements using WIBOR are defective or invalid.

Existing agreements should be analysed according to the terms on which they were concluded and the law in force at the relevant time.

If the bank proposes a change of benchmark, an annex or new interest terms, it is worth checking before signing what impact the document will have on the further performance of the agreement.

What claims can you pursue?

The scope of possible claims depends on what irregularities are found during the analysis of the agreement.

Depending on the specific case, the dispute may concern, among other things, the effectiveness of certain contractual provisions, the amount of payments collected or the way the interest rate was set.

However, we do not assume that every case will result in “removing WIBOR” or invalidating the agreement.

We first analyse the legal basis for the claim and the possible financial effects, and only then assess whether it is justified to take the case to the bank or to court.

Settlement or annex proposed by the bank

The bank may offer the borrower a change in the terms of the agreement, a switch to a fixed interest rate or the use of a different benchmark.

Such an offer may be beneficial, but before accepting it, it is worth establishing its real consequences.

We analyse, among other things:

• the new interest rules,

• the length of the fixed-rate period,

• how instalments will be set in the future,

• changes to other provisions of the agreement,

• any statements concerning the existing agreement and claims.

It is particularly important to check whether, by signing the annex, the borrower is making additional statements that go beyond the change of interest rate itself.

What documents do we need?

The basis of the analysis is primarily the loan agreement together with the terms and conditions and attachments.

Other useful documents may include:

• annexes to the agreement,

• information forms,

• simulations received before taking out the loan,

• the repayment schedule,

• the interest rate history,

• the loan repayment history,

• correspondence with the bank,

• documents concerning proposed changes to the loan terms.

On this basis, we can assess how the interest rate was structured and what information the borrower received.

Legal assistance in matters concerning WIBOR

WIBOR cases differ from Swiss franc cases and require careful analysis.

Current case law does not provide grounds for automatically challenging all variable-rate agreements, but the way the agreement was structured and how the disclosure obligations towards the consumer were fulfilled still matter.

That is why we start every case with an analysis of the documentation and the actual terms on which the loan was taken out.

Our aim is to establish whether the specific agreement gives grounds for action against the bank and which solution will be most justified from the borrower’s point of view.