mBank to replace WIBOR with POLSTR for new mortgage loans

mBank has announced it will transition its mortgage offerings to the new POLSTR 1M Compound Rate reference index. Starting October 7, 2026, the bank will stop selling new mortgage loans based on the WIBOR index, replacing them with products tied to POLSTR.

New applicants will have the option of a variable interest rate based on the POLSTR 1M Compound Rate or a fixed-rate option for the first five years. If a fixed rate is chosen, the interest rate will revert to the POLSTR index after the initial five-year period unless a new fixed period is agreed upon. Existing mortgage holders with WIBOR-based loans will see no changes to their current terms and do not need to take immediate action.

This transition is part of a broader reform in Poland to replace WIBOR with POLSTR. While WIBOR will remain available for existing products, new loans indexed to WIBOR will no longer be available starting January 1, 2027. The WIBOR index is legally scheduled to be phased out entirely by December 31, 2036.