POLSTR reaches new Polish mortgages as the WIBOR transition moves into retail banking

Poland’s move away from WIBOR is becoming a retail mortgage event rather than only a market-infrastructure reform. Erste Bank Polska said that from 26 September 2026, information forms for applicants seeking a new mortgage would use the POLSTR 1M Compound Rate for variable-rate pricing instead of WIBOR 3M.

The benchmark will apply both to mortgages that are variable from the beginning and to the variable-rate phase after a five-year fixed-rate period. Under the new structure, the interest rate is recalculated each month. That differs from the previous WIBOR 3M model, where the reset occurred every three months.

The change applies to new applications, not automatically to existing mortgages. Erste also said clients who had already received a WIBOR 3M information form by 25 September could continue under that basis if the loan is approved.

KNF designated POLSTR a significant benchmark in August. Its updated reform roadmap says WIBOR and WIBID should stop being used in new contracts and financial instruments from the beginning of 2027, with narrow exceptions for derivatives used to manage legacy risks.

For homebuyers, the key point is mechanics rather than a directional rate call. A POLSTR-based loan may react to short-term market rates on a different timetable from a WIBOR 3M loan, but total borrowing cost still depends on the benchmark, bank margin, fees, fixed-rate period and future rate path.