WIBOR — what it is and how it affects your loan

Quick Answer

WIBOR (Warsaw Interbank Offered Rate) is the reference interest rate in the Polish interbank market, representing the price at which commercial banks are willing to lend to each other. It is the basis for interest rates on most mortgages in Poland, where the rate equals WIBOR plus a fixed bank margin. Common variants are WIBOR 3M and WIBOR 6M, updating the installment quarterly or every six months. WIBOR follows the NBP reference rate but sits slightly higher because it embeds interbank credit risk, and it is being replaced by the transaction-based WIRON benchmark.

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Definition

WIBOR (Warsaw Interbank Offered Rate) is the reference interest rate in the Polish interbank market. It represents the price at which commercial banks are willing to lend money to each other. It is the basis for interest rates on most mortgages in Poland.

How WIBOR affects your installment

The interest rate on a variable-rate mortgage consists of two elements:

Interest rate = WIBOR + bank margin

Example:

• WIBOR 3M: 5.80%
• Bank margin: 2.00%
• Interest rate: 7.80%

The margin is fixed for the entire loan period. WIBOR changes — and it's what causes installment increases or decreases.

Types of WIBOR

The most popular in mortgages are WIBOR 3M and WIBOR 6M.

WIBOR vs NBP rates

WIBOR follows the NBP reference rate but is not identical to it. Usually WIBOR is slightly higher than the reference rate because it includes credit risk between banks.

When MPC raises rates → WIBOR rises → Your installment rises. When MPC lowers rates → WIBOR falls → Your installment decreases.

WIRON — WIBOR's successor

Since 2025, there's an ongoing process of replacing WIBOR with the WIRON (Warsaw Interest Rate Overnight) indicator. WIRON is based on actual overnight transactions, not bank declarations. For borrowers, this usually means a lower base indicator — but banks may compensate with higher margins.

How much does a WIBOR change cost you per month?

Loan 400,000 PLN, 25 years, margin 2%:

The difference between WIBOR 2% and 7% is over 1,200 PLN monthly.

How Freenance can help

Freenance helps monitor WIBOR's impact on your finances:

• Loan installment tracking and its changes over time
• Scenario simulation — what happens when WIBOR rises/falls
• Impact on Runway — how installment changes affect your safety cushion

👉 Monitor your finances with Freenance — freenance.io

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FAQ

What is WIBOR and who sets it?

WIBOR (Warsaw Interbank Offered Rate) is the reference rate of the Polish interbank market, calculated by GPW Benchmark from declarations of a panel of banks. It is not set by a single institution but determined daily from rates at which banks declare they would lend funds to each other.

What is the difference between WIBOR 3M and WIBOR 6M?

WIBOR 3M is recalculated every three months, so a variable-rate mortgage installment based on it adjusts quarterly. WIBOR 6M updates every six months, which means slower reaction to rate changes — useful in falling-rate environments but slower to benefit you when rates drop.

Does WIBOR move in lockstep with the NBP reference rate?

WIBOR follows NBP decisions but is usually slightly higher because it embeds interbank credit risk. Sharp NBP rate changes typically translate into WIBOR moves within days, although the spread between them can widen during market stress.

How does WIBOR affect my monthly mortgage payment?

Your installment is based on WIBOR plus a fixed bank margin. When WIBOR rises by 1 percentage point, the interest portion of your payment rises by roughly 1 percentage point on the outstanding balance, which on a 400,000 PLN, 25-year loan can mean a couple of hundred PLN more per month.

Is WIBOR being replaced by another benchmark?

Yes — Polish authorities have approved WIRON as a transaction-based successor to WIBOR, with a multi-year transition period. New mortgage contracts and existing loans are expected to migrate to WIRON or a successor benchmark, though timelines have shifted and you should check current regulator guidance.