POLSTR Will Replace WIBOR. What It Really Means for Your Installment - and What Is Still Unknown
Jun 25, 2026
POLSTR Will Replace WIBOR. What It Really Means for Your Installment - and What Is Still Unknown
For several months, one slogan has been appearing in the headlines: WIBOR is disappearing, POLSTR is coming in. For many people repaying a mortgage, it sounds worrying.
However, it's worth separating facts from speculation. The reform is already a foregone conclusion, but many of its details remain undecided. Meanwhile, some publications present them as a certainty.
What is POLSTR
POLSTR stands for Polish Short Term Rate. It is a new reference rate that is to replace WIBOR as the basis for the interest rate on loans with a variable interest rate.
The most important difference lies in the way it is calculated and the nature of the indices:
| Feature | WIBOR | POLSTR |
|---|---|---|
| Calculation method | Bank declarations | Real transactions |
| Nature | Forward-looking | Backward-looking |
| Data source | Bank quotations | Actual market operations |
| Resistance to manipulation | Lower | Higher |
MOST IMPORTANT DIFFERENCE WIBOR is based on bank declarations regarding the cost of money in the future and is "forward-looking". POLSTR is based on real, one-day transactions concluded between banks and reflects what has already happened on the market. Greater transparency was the main argument for the reform.
What the indices are today
Currently, POLSTR is slightly lower than WIBOR. However, this does not automatically mean lower loan installments.
| Index | WIBOR | POLSTR (Compounded Rate) |
|---|---|---|
| 1M | 3.78% | 3.57% |
| 3M | 3.84% | 3.53% |
| 6M | 3.91% | 3.64% |
As of June 24, 2026, GPW Benchmark.
Key dates of the reform
The change will not happen overnight. It is a process spread over many years.
| Deadline | What is happening |
|---|---|
| Until the end of 2026 | Transition period and implementation of products based on POLSTR |
| From January 1, 2027 | New contracts can be concluded exclusively on POLSTR |
| Until the end of 2036 | WIBOR remains in existing contracts |
| January 1, 2037 | Final liquidation of WIBOR |
IMPORTANT CHANGE The reform schedule has been extended by almost a decade. Until recently, the phasing out of WIBOR was planned for 2028. Currently, the deadline has been moved to January 1, 2037.
The reason is practical. The average mortgage in Poland is repaid much faster than the schedule would suggest. Many existing contracts will end naturally before WIBOR is completely withdrawn.
I have a loan based on WIBOR. What should I do?
In most cases, the answer is: nothing.
If you are currently repaying a loan based on WIBOR 3M or WIBOR 6M, your contract remains valid and operates on the current terms. The planned change of index is to happen automatically, without the need to sign annexes or visit the bank.
FOR CURRENT BORROWERS The reform does not mean the need to take immediate action or renegotiate the contract.
Will the installment drop after switching to POLSTR?
This is the most frequently asked question and at the same time the biggest misunderstanding. POLSTR is currently lower than WIBOR, so it's easy to assume that after the change, the installment will automatically drop. However, this doesn't have to be the case.
ECONOMIC NEUTRALITY It is planned to apply a so-called adjustment spread, whose task will be to equalize the difference between the indices at the time of switching to the new system. The goal of the entire reform is to maintain full financial neutrality.
That's why it's not worth postponing a credit decision solely in the hope of a lower installment after changing the index. Loan costs are still primarily determined by other factors:
| Key factors | Meaning |
|---|---|
| Bank margin | Directly affects the interest rate |
| Creditworthiness | Determines available offers |
| Type of interest rate | Fixed or variable |
| Offer parameters | Commissions, additional costs, bank conditions |
What is still unknown
Although the general direction of the reform is already known, several key elements remain in the sphere of arrangements.
| Status | Scope |
|---|---|
| Certain | WIBOR will be phased out, and new contracts will be based on POLSTR |
| Undecided | Exact amount of the adjustment spread |
| Undecided | Detailed legal rules for replacing indices in existing contracts |
| Expected | Solutions prepared by the Ministry of Finance |
It is these as-yet-undecided details that may have a real impact on the situation of borrowers in the future.
What this means for you
If you have a loan based on WIBOR today, you don't need to take any action. Your contract remains valid for many years to come.
If you are just planning to buy a property on credit, the name of the reference index itself is currently less important than choosing the right offer and type of interest rate.
MOST IMPORTANT CONCLUSION WIBOR and POLSTR are not key factors in choosing a loan today. The bank margin, offer conditions, and the decision between fixed and variable interest rates have a much greater impact on the cost of financing.
FREE CONSULTATION Planning a loan or wondering how the reform will affect your contract? A credit expert at NaszEkspert.pl will explain what the change of index means in your situation and help you compare available offers. Check how the reform may affect your loan.
Sources: Index values: as of June 24, 2026, GPW Benchmark. WIBOR liquidation date (January 1, 2037): GPW Benchmark announcement of May 18, 2026. Other information: Ministry of Finance, Polish Bank Association, and National Working Group for the reform of reference indices. Some elements of the reform remain in progress and may still change.
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