WIRF instead of WIBOR: will your mortgage installment finally fall?

The introduction of WIRF does not guarantee lower installments, because this indicator is based on overnight transactions, which may cause greater volatility in loan costs compared to the forecast-based WIBOR. This change represents a fundamental restructuring of the financial architecture, shifting the burden of market risk from the bank directly to the borrower's wallet.

For decades, WIBOR was the foundation of the Polish mortgage market, based on term valuations. Banks declared the cost of obtaining capital over a three- or six-month horizon, which in practice meant a built-in term risk premium. Such a structure acted as a shock absorber – it smoothed out sudden interest rate movements, offering borrowers predictability, even if the cost of money was inflated at the time. WIRF (Warsaw Interest Rate Factor) is a transaction-based overnight indicator that reflects the real cost of money "here and now." Unlike its predecessor, WIRF does not smooth the market curve.

The National Bank of Poland and the Polish Financial Supervision Authority have for years pointed to the need to move away from indicators based on bank estimates. The WIBOR mechanism, based on rate declarations, raised concerns among regulators regarding the transparency of interbank trading. The introduction of WIRF is a direct result of the EU's BMR (Benchmark Regulation), which requires reference rates to be based on actual, hard transactions. Brussels imposed rigorous standards, aiming to eliminate the possibility of manipulation, which in the past cast a shadow over the credibility of interbank rates.

For a mortgage holder with a loan of PLN 500,000, the transition to the new indicator means a change in the scale of risk. If WIRF rises by 0.5 percentage points as a result of sudden liquidity tension in the interbank market, the loan installment may increase by approximately 208 PLN per month. On an annual basis, this means an additional expense of around 2,500 PLN. With WIBOR, which averaged costs over time, such a jump would be much more diluted and less noticeable in the short term. WIRF reacts immediately, which, given high interest rate volatility, translates into drastic fluctuations in the amount of monthly transfers to the bank.

Financial analysts monitor interest rate fluctuations on the stock exchange.

The mathematical construction of WIRF eliminates the term risk premium. The absence of this margin makes this indicator a mirror of the decisions made by the Monetary Policy Council (RPP). Every RPP meeting, every change in the central bank's communication, is immediately priced in by the interbank market. In times of economic stability, this may mean lower costs, but in periods of inflationary turmoil or liquidity crises, the borrower becomes a hostage to daily market fluctuations. The stability we have become accustomed to over the last 30 years is being replaced by systemic sensitivity to every piece of information flowing from the economy.

Banks do not intend to remain passive in the face of new risk dynamics. The introduction of WIRF forces financial institutions to revise their loan pricing models. Since a bank can no longer rely on smoothed WIBOR forecasts, it must protect itself against volatility in other ways. Analysts from the banking sector point out that the most likely scenario is an increase in loan margins. If banks decide that debt servicing costs have become too unpredictable, they will pass this cost on to the client in the form of a higher fixed margin. As a result, the nominal drop in the base interest rate may be fully consumed by the increase in the bank's margin, which for the borrower means a status quo in terms of costs, while simultaneously increasing the risk of installment volatility.

It is worth looking at historical data, which shows how overnight-type indicators behaved during periods of high inflation. When the interbank market experienced temporary liquidity shortages, overnight rates were capable of recording sharp jumps, which on a monthly basis produced a very uneven cost curve. WIBOR 3M, due to its construction, was "resistant" to such one-day anomalies. WIRF, on the other hand, will fully transmit them to borrowers' wallets. What is theoretically supposed to be fairer and more transparent becomes, in practice, a tool that transfers full market volatility to the consumer.

The KNF emphasizes in its communications the importance of the financial system's resilience, but for the average Pole, this resilience means the necessity of building much larger financial buffers. If a loan installment can increase by several hundred zlotys in a single month just because there was a technical liquidity shift between banks, the household budget loses predictability. The borrower ceases to be a party to a contract with a bank and becomes a participant in the interbank market, where the price of money changes every day.

Loan documents in the hands of a bank client.

The process of implementing WIRF is also a technological and legal challenge. Banks must update thousands of loan agreements, amend agreements, and adapt IT systems to handle an indicator that is not "determined," but "calculated" based on transactions. The costs of these operations are real and burden the banks' balance sheets, which is another argument for the boards of financial institutions to raise margins. Borrowers should not expect the indicator transformation to be financed by bank profits. The client will pay for the change in reporting standards, either through a higher margin or through higher operational commissions.

Analyzing the scenario for 2026, one must take into account the impact of fiscal policy on the money market. If the budget deficit remains high and the state's borrowing needs force the absorption of liquidity from the banking sector, WIRF may be under constant upward pressure. Unlike WIBOR, which was anchored in term expectations, WIRF will reflect current pressure on liquidity in the system. This means that every treasury bond auction that attracts the attention of banks will have a direct impact on mortgage interest rates.

For holders of variable-rate loans, a defensive strategy becomes the only logical solution. Switching to a fixed interest rate, offered by banks for a specific period, is the only method to mitigate the risk of WIRF volatility. However, it is worth remembering that banks price fixed rates based on long-term market forecasts, which already take into account the risk of introducing the new indicator. In other words, banks are already "pricing in" WIRF volatility in their fixed-rate loan offers, which makes this protection expensive.

The borrower must ask themselves: can I afford the flexibility that WIRF provides if I receive a financial rollercoaster in return? Many people chose WIBOR out of habit, without analyzing its construction. Now, the change in the indicator forces financial education. Understanding the difference between a transaction-based overnight rate and a term-based declaration rate ceases to be niche knowledge and becomes a survival skill in a relationship with a bank.

Visualization of market indicator volatility.

The role of public communication in the process of this change cannot be ignored. Banks and supervisory institutions should clearly communicate that WIRF is not a "cheaper WIBOR," but a "different WIBOR." Any attempt to present this indicator as a cure for high installments is a cognitive bias. If the base rate falls, but the bank's margin rises, the total cost of the loan will remain at a similar level or increase. This simple truth is often lost in the maze of financial jargon that accompanies the reform of reference indicators.

The borrower should verify whether their contract contains clauses allowing the bank to unilaterally shape the margin in the event of a change in the base indicator. Many contracts signed years ago have provisions that give banks a wide range of maneuver in extraordinary situations. The reference indicator reform may be interpreted by some institutions as a sufficient reason to revise pricing terms. Careful reading of annexes and general terms of the contract is now a duty, not just good practice.

If we look at foreign markets where similar reforms have taken place (e.g., the transition to risk-free rates in the USA or Great Britain), it is clear that transition periods were characterized by great uncertainty. In Poland, where the mortgage market is largely based on variable rates, the scale of this challenge is incomparably greater. The lack of long-term hedging instruments for individual clients means that we are in a unique situation where all systemic risk is distributed across millions of households.

The NBP's actions regarding maintaining liquidity in the banking sector will be crucial for the stability of WIRF. If the central bank consistently provides liquidity, indicator fluctuations may be limited. However, in crisis situations, when the central bank restricts the money supply, WIRF may shoot upward without waiting for formal interest rate hikes by the RPP. This is a real risk that was not visible with WIBOR.

Many people ask themselves whether it is possible to negotiate better margin terms when switching to WIRF. In practice, banks offer standardized annexes in which the room for negotiation is negligible. The only real way to optimize costs is to compare offers from different banks, which may have different approaches to margin policy after the introduction of the new indicator. Some institutions may use this change to attract clients with a lower margin, while others will focus on maximizing profits in response to higher operational risk.

Concluding the reflections on the impact of WIRF, it should be emphasized that the transparency of the financial system has its price. While previously we paid for the "smoothing" of rates in the form of higher margins hidden in WIBOR, now we pay with the direct risk of installment volatility. This is a paradigm shift – from a system based on trust in banks' "estimates" to a system based on "hard" market data. Is this beneficial for the borrower? The answer is: it depends on each of our risk management skills.

Questions and answers

Will WIRF automatically lower my installments?

No, WIRF is not inherently lower than WIBOR; it is a transaction-based indicator that can be higher during periods of tension in the interbank market. Its level depends directly on current liquidity in the banking sector, not on long-term forecasts.

Can I avoid the changes introduced by WIRF?

The only way to avoid the volatility of reference indicators is to take advantage of a fixed-rate loan offer for a specific period. This allows for freezing the interest cost for a certain time, regardless of WIRF movements.

Why was WIBOR considered less safe?

WIBOR was based on bank declarations, which theoretically allowed for manipulation and a lack of reflection of the real cost of money. WIRF is based on actual transactions, which increases the objectivity of the indicator, but at the same time makes it more susceptible to market liquidity fluctuations.

What happens if the interbank market has liquidity problems?

In the event of a liquidity crisis, the WIRF rate can rise sharply in a very short time. This means that the loan installment can increase suddenly without a transition period, which poses a significant threat to the stability of the household budget.

Can banks raise margins after the introduction of WIRF?

Yes, banks can raise margins to compensate for the risk resulting from the greater volatility of the WIRF indicator. This is a way for them to secure profits in a new regulatory environment where they can no longer rely on the "safety valve" of term-based WIBOR forecasts.